Dogecoin are listed in US regulated exchanges Coinbase and Bittrex. Whatever words and posts Elon Musk is doing are just part of his freedom. Unless he was forcing people to invest in Dogecoin then there is a valid case. Dogecoin with or without Elon Musk hypes still probably made an ATH last year just like most of the other top 100 coins due to the bullish season in the crypto market.

The fact that the complainant mentioned that they are aware since 2019 that Dogecoin has no value, made him just a sore loser in an open market regulated by US authorities. It is more reasonable for the complainant to question US authorities assigned for allowing exchanges like Coinbase to list Dogecoin.