I personally wouldn’t give him a mutant gem
Given that you already have OR, Colossus, and AA awakened, definite yes. I used one for mine and find it to be really helpful - particularly if like me you are not a 100% perfect player all of the time. The incoming damage cap to help with the occasional mistake as well as the extra damage on heavy are really helpful - particularly for the occasional fight where you aren’t fighting someone #metal.