It's his money, so he can do whatever he wants with it. But not all things that are legal, are moral.
Trying to hobble a political adversary with onerous lawsuits is chickenshit. I would expect nothing else from 'Crats. Playing dirty, afflicting innocent people with injury, loss and undeserved burdens is the 'Crat specialty.
DJT is big enough to handle the flak - but there's gonna be some blowback to people who moved against him if and when he's reelected.