I'm pretty sure that there's nothing Jack can do about this, I believe it technically falls under freedom of speech, just like musicians get. He can't really even claim defamation of character unless the character is specifically named after him.

I'm pretty sure if nothing can be done about something as obvious as this:
http://www.megaforcerecords.com/mini...lood-cover.gif

then nothing can be done about an even more vague statement in a video game.