Because Disney has not responded to his legal team. Unfortunately ADF has cancer, needs the money now, and may not be alive to collect even should he prevail. It's not uncommon for such suits to be indefinitely delayed for years & years through any number of tactics. A lawyer willing to take on this case in courts would have a lot of expenses, and probably require a significant contingency. The amount of money involved here, when going up against one of the largest companies on Earth, may not be enough to cover the costs that would be incurred, in which case no lawyer would take the case. Even if they do, and ADF prevails, he's looking at the prospect of receiving half, maybe less, than what he is owed.
> Because Disney has not responded to his legal team.
This really has no bearing on whether or not to file a lawsuit. If that was the case, the best way to deal with any lawsuit is to simply ignore it. File a suit and Disney has to respond.
On the other hand, they certainly can delay this. Even if penalized for doing so, what's that to them? I suspect public pressure is the real motivation here.
That was only one consideration, taken out of context you're correct: It does not fit. If this latest gambit doesn't work, it looks like their next step will be to file a lawsuit. But that doesn't have to be the immediate step. Once taken, any somewhat more amicable solution is taken off the table.
They've pursued these possibilities:
1) Hey, maybe you've overlooked this, but you haven't been sending me royalty reconciliation statements & payments. (This actually happens without malice: I worked at a scientific publishing company, and when a reprint of an old book happens, or the rights to another book are purchased, the royalty obligations are not always 100% clear, or the 3rd listed author on something is overlooked, or the author is dead and an estate has to be tracked down, or any number of other issue)
Next they went to:
2) Okay, we'd like to sit down with our lawyers to figure out the specific contractual issues here and work something out.
Now they're at:
3) It seems like you aren't dealing with us in good faith. We represent a large group of creative writers you may need to work with in the future, those creators have a vast number of fans that are your customers. Maybe that public reminder will help your willingness to address this issue.
All of the above are options that can play out fairly quickly. A lawsuit is not fast. And as I said, once you go down the lawsuit route, the above options are off the table.