Okay let's explain /clarify some stuff and correct mistaken information
Joe has not gone straight to the executors, Joe had filed 2 separate lawsuits against the estate.
Lawsuit 1. Joe claimed that the will was not valid, Branca should not be an executor etc. Judge rejected that case saying that Joe did not have a legal standing in contesting the will. Oxman filed an appeal. We don't know the result of the appeal.
Lawsuit 2. Joe requested an allowance from the estate saying that he was dependent on Michael and Michael gave him money through his mother. This case is still ongoing (judge did not decide on this case). And the deposition is for this case.
Deposition is a legal term. A deposition is a discovery where you gather information and evidence. Deposition happens outside the court but under oath where lawyers and a court reporter is present and the deposition is transcribed (in some cases it might even be filed with the court). The other side (in this case the estate lawyers) do the deposition to gather information (such as why joe thinks he was dependent on Michael, how much money Katherine gave him when Michael was alive, how much money he needs and why etc etc). All of the information gathered at a deposition can be used in the trial. Similarly information gathered in the deposition can be used to determine to whether go to the trial or settle outside the court (such as if they believe Joe has a strong evidence they might offer him a settlement or if they believe he has no evidence they might reject anything and take it to court).
Now there's nothing strange or fishy about a settlement / offer outside the court. As you can see from this example even a simple case takes months, requires effort, time and money. In small cases such as this it's recommended to try to settle outside the court as its quicker, easier and cheaper. Plus settlements are private - court documents/lawsuits are not. In some situations privacy (such as keeping the amount of money given private or keeping the terms of the settlement private) could be enough reason to settle outside the court. There can be tens, hundreds of reasons for settlement which are quite normal and acceptable.