Some change-of-pace stuff with Malik would be interesting, maybe effective, but he can't be "the starter" yet.
My own view is that , given the c--p deal he has been handed by Bill, Mac is owed the rest of the season to show what he can do. We can forget about giving primacy to winning the game: this year's record is irrelevant, except re our draft position. Many, I understand, feel they know as much about Mac as they need to know. I understand that view.
As for Grier or some "veteran" castoff, why bother? There is NO chance such options can develop into the long-term starter.
TBH, I don't think it really matter who plays QB. This season is now 100% about next year and years following. I'd focus on depriving Bill of any and all GM responsibilities, asap, as in yesterday.