Doesn't seem strange to me. If I am suing a company for false advertising I'll claim that their behavior was aimed at inducing me to purchase the product at an inflated price. Not because I think they were specifically conspiring to target those lies directly at me personally, but because I am the one that is a party to the lawsuit. If Twitter was lying to inflate the stock price in general, then they were inducing everyone to buy at an inflated price and Musk is one of those people.