Oh I agree. But I'd be willing to bet there were plenty of people who saw the movie without ever reading the comics who assumed it was based on the cartoon. I don't think anyone thought it was based on the game. Which is why I'd be willing to listen to that person's argument, even though it's based on ignorance.
Regardless, I don't think it counts for consideration, any more than the Spider-Man or Captain America movies or whatever count, just because they had a game before they had a movie. Just like TMNT, the comics came first, and everything after is based on those.