You want to know why this is funny as shit?
Because what he did wasn't from a place of racism, as you previously pointed out.
This wasn't like Blackface in the 30s, where white people were performing as caricatures of Black People in general, for the purposes of making fun of them.
He was impersonating a specific person. Who happened to be of darker complexion. And not in order to make fun of them, but to honor their performance.
Imitation is the sincerest form of flattery after all. And Justin isn't the only one to have done this with those benign intentions in mind.
But Justin has been at the forefront of creating, and pushing, a culture that does not want, or care, to distinguish the difference in motivation when others have done this and similar things. Justin has pushed for a society that is so incensed and offended at the slightest little thing, that no one even wants to look at if something was done from a position of malice, or from a position of reverence.
Mens rea doesn't factor into his, or the left's criteria for judgment and punishment of others. Something Justin has demonstrated again and again in his tenure as a politician. Something regular people labelled as "right wing" have long argued as being ridiculously intolerant, and totalitarian.
So when Justin is caught doing the same type of innocent acts he has so heavy hand-idly excoriated others for, it is only fitting that he be hoisted on his own petard. And that the Left learns that there is a hell of a lot more grey areas in human social interaction, then their agenda leaves room for.
This is why the "Far Right", as you label them, is being sanctimonious right now. Because the Left made this particular bed. Now they can sleep in it.