I don't see the problem with it. How is this different from Fox, MSNBC, etc?
The guy ran a historic, nation wide, and unusual political campaign. If Mike Huckabee can have a show on Fox I don't understand how this guy merely being a commentator is worse.
Mike Huckabee happened to be a governor for 11 years and won 8 states in the 2008 primaries... not really comparable.
Plenty of senior campaign staffers end up on cable news. MSNBC, for example, loads its roster full of Republican Presidential campaign staffers - Nicolle Wallace, Steve Schmidt, Ben Ginsburg, Rick Tyler, etc. - but all of them are far more "respectable" than Lewandowski, who is plagued with controversy. Even people who didn't like Cruz like Rick Tyler, and even people who didn't like Bush/McCain like Nicolle Wallace. I don't know anyone who actually likes Lewandowski or is interested in what he has to say.