Which was adopted by trolls as a "white power" sign, very much to muddy the waters as to what is or is not an intentionally racist gesture, and to have fun with the idea of offence and racism at the expense of anyone that might possibly be offended.

So when you see people, who are well aware of this meaning, using it in a photo like that, what they're saying is "ha ha look how funny the idea of us being racist is". Which of course is actually just normalising white supremacy, and enabling it to go unchallenged by shifting the line between overt racism and coded racism, and preventing any good faith discourse.

So this is either intentionally racist joking-but-not-really on his part or incredibly crass idiocy that provides cover for other racists.