It’s a very fine line they would have to walk. It must be believable to the average person that the claims are true. It must not actually be true. It must be done with (the appearance of) malice. It must not be done as a criticism/satire of the target and their actions.

And on top of that, their publicist/PR must think a lawsuit will get them more than they lose. Once it’s aired, it is out there forever. It could then be the one that everyone seeks out and shares with friends, as “the one that Tom Cruise sued to get rid of”. This is known as “The Streisand Effect”.