Well, if American McGee wants to rebuild the franchise from scratch, then he faces the exact same problem, doesn't he?
If EA wants to remake the franchise, they're basically saying "Look, we filed the serial markers off, here's a new Dark Alice in the Wonderland IP", and they know nobody will buy it.
If American McGee wants to remake the franchise, it's basically "Look EA, we can't actually remake the Dark Alice in the Wonderland IP, but here's Wark Dalice in the Anderland IP", and none of the EA's lawyers will buy it, and he get sued to oblivion by EA.
It's an extermely uncomfortale stalemate regardless of the fact that the original stories were in public domain.
Sure, American McGee can go "well fuck it, here's a super fucking cute and lore-friendly happy trippy Alice in the Wonderland remake that totally goes to a whole different direction this time, HEY BACK OFF DISNEY LAWYERS, I said totally different direction", but that's no longer American McGee's Alice, now is it?