I do not understand why this should be a lawsuit though. I mean I get that he "wanted to invest" into stake, and be part of it when it first started. But just because he was part of primedice, and didn't get accepted as fellow founder to stake doesn't mean that he is owed anything.
Apparently Tehrani and Eddie didn't want to work with him and thats it, thats literally the only reason for him not being part of it, there is no secret behind it. If someone doesn't want to be partners with you, then you can't force them to be partners with you. This is why it will drop very quickly, he will not be paid 400 million, if stake feels generous, they can give him a few millions at best and close the door, or maybe not even pay a dime.