Their case isn't frivolous. A lot of states have anti-boycott laws (fuck you very much, AIPAC). Decide on your own not to do business with an asshole, fine. Collude with others to make sure none of you do business with the asshole, not so fine. And they judge-shopped themselves Reed O'Connor, who is a favorite of right wing causes. This suit will not be throwm out.
Oh, and Musk isn't pursueing advertising, he's looking for damages (cash).