Well, he is and has been Trump's personal goon for some time, but even Trump wouldn't have put Rudy the Rat on this case if dozens of other lawyers hadn't said "no, thanks." I mean, the money's good (assuming that Trump pays the bill, which is far from a given), but it kills your reputation if you file futile suits that have no basis in fact and are certain to be thrown out.
Rudy the Rat, though, has no remaining reputation to tarnish. He sold his soul and his ethics, if he ever had any, to Trump quite a while ago. The loony-bird theory he's touting is beyond ridiculous, of course, but I don't think his babbling that theory at press conferences actually hurts him. Sort of like if we all found out that Jeffrey Dahmer never paid his utility bills.
I'm surprised that our loyal Trumpers haven't rushed to the defense of their orange hero and screamed that the election was rigged. Maybe even THEY are too embarrassed to support that jerkwad at this point.