i see no problem with wearing make up to look like the star being impersonated... fallon as chris rock, kimmel as whomever he was supposed to be...
minstrel makeup is a racist statement as in the clintons and the virginia governor, but make up to play a role has no racist undertones... like in robert downey jr. role... it dealt with that in the script.
no apologies from fallon necessary
But I must admit I have a nice big case of Schadenfreude whenever I see any lefty hoisted on their petard.