When company is go longer public and you own it, what argument somebody would have to sue you for?

1. first of all, as you said he did it already and Twitter got sued, second of all the point of corporation is to isolate owner of the liability. Sure they can sue Twitter, but if company doesn't exist anymore too bad. They could go after remaining assets, but that's it.
2. they are not shareholders, they are giving him a loan. If you get a loan and lost the money, the bank (or a loan shark) doesn't give damn if losing the money was your fault or not

The theory that he is purposefully destroying his company is just dumb, there's no upside for him to do that.