No, it's not delayed discovery.
In simple terms equitable estoppel means that statutes of limitations can be lifted if the accuser can show that the reason why he missed to file within statutes is because of some deliberate conduct by the defendant or his representatives. Typically a threat or misleading the victim about his legal possibilities. For example, in cases of child abuse the alleged victim can say that he was threatened by the abuser. I'm going to illustrate it through one of the precedent cases Robson uses in his lawsuit (which in my view is rather counter-productive for Robson because comparing his case to this one just highlights how ridiculous his request for equitable estoppel is):
Doe vs. Bakersfield City School District (2006)
Here the accuser said he was sexually molested by a teacher in high school and the abuse continued even beyond that until he was about 20 years old. When he left school the teacher went after him, always did things to be near him, to have access to him. Meanwhile he threatened him saying he had people in high places and if the victim ever told he would ruin him.
The abuse stopped around 2000 and he filed his lawsuit in July 2002, so it's not like it took him 20 years to realize what was abuse or something. In fact he first disclosed his abuse to his girlfriend in November or December 2001. Then the girlfriend ("A") immediatly called the abuser to confront him:
After A.'s call, Diaz contacted plaintiff and said he wanted to see him.   A. called Diaz again and told him to stay away from plaintiff.   Diaz replied, “You better watch out because he doesn't know what he's doing.   I'll get him.   This is going to ruin him if it's going to ruin me.”
Law enforcement was also contacted right around that time. Although the abuse stopped in 2000, the abuser kept calling and threatening the victim and in fact there were threats made by the abuser even after law enforcement was contacted:
In February 2002, A. and plaintiff were driving by Diaz's sister's house when they spotted Diaz outside unloading groceries.   A. rolled down the window and yelled, “You can't face the truth;  you want to hide from it!”   Diaz yelled back at plaintiff, who was in the passenger seat of the car, “I can't believe you're doing this to me!   You're going to be very sorry!   You should have kept your mouth shut!”
Now, this is totally different from the kind of narrative Wade is telling, ie. that MJ told him in 1993 they would both go to jail and that both of their carreers would be over and that just had such a profound effect on Wade that he was unable to acknowledge his abuse until he was 30. Despite of seeing that no other accuser of MJ ever went to jail.
Here we have stalking and direct threats from this teacher that he would take down and ruin the accuser which continued until basically the accuser reported the abuse and even after.
So these are the type of things where equitable estoppel is usually granted. But what does Wade claim?
He claims that MJ threatened him in 1993 that they would both go to jail and brainwashed him into thinking that anal rape was love which he still believed as an adult man and with the 1993 and 2005 cases behind us, and therefore he was unable to disclose his alleged abuse until 2012. I can't see how that BS would be a reason for equitable estoppel. How can anyone belive that MJ's alleged threat that they would both go to jail reasonably had such a grip on him until he was 30, when he could see that no other accuser of MJ ever went to jail? How can anyone believe that he did not know until 2012 that anally raping and sexually molesting children was illegal? Yes, he claims that:
So why did he think MJ was on trial in 2005 if he did not know until 2012 that such acts would be illicit? BTW, this is yet another contradiction in his claims: on one hand he claims he believed both he and MJ would go to jail if it came out - ie. it was illicit by both of them. Then in another statement he makes he claims he was not aware of the illicit nature of it at all. So which one is it?
Moreover, even if we believe everything he says about MJ molesting, threatening and brainwashing him and Wade not knowing until 2012 that anally raping children was wrong and we believe that MJ telling him at 11 that they would both go to jail had such a profound effect on him that he was unable and unwilling to realize his abuse until he went to therapy in May 2012, even then he is outside of statutes. Probate Code 9103 acknowledges the possibility of a late discovery of someone's injury and in that case it gives the claimant the possibility to file within 60 days after discovering the facts giving arise to the claim. Ie. in this case Wade says he discovered and was able to acknowledge for the first time that he was abused on May 8, 2012. That means by Probate law he should have filed until July 8, 2012. He missed that. So I have no idea what kind of equitable estoppel could be ivoked for that for him. MJ was dead at the time so he could not do anything to prevent Wade from filing a claim within 60 days. And there is nothing that Wade claims about the Estate blocking him, threatening him or anything like that.
As I see it he is trying the angle that he was so brainwashed and so severly manipulated by MJ that even after realizing his abuse for the first time in May 2012 that still prevented him from making a timely claim within the possibilities of Probate Code 9103. But if this is accepted by the court then I think they might as well as abolish statutes of limitations altogether. Because like we talked about it above, then anyone can make any claim about being brainwashed and that could be used as an excuse for any untimely claim.