I'm not sure why a photographer, who has been documenting all elements of Brixton life in pictures for a very long time, should have to justify one set of images showing one local event because it has too many young white people having fun and may/may not be representative of the oft discussed gentrification issues affecting the local community.
Those images may do that, or not, but a photographer who simply documents the area is just showing more images from the area. What those images say about the area or how the area might be changing for better or worse is not for the photographer to defend. It just is what it is.
I'll admit I looked at that set of pics and thought 'young, white, wealthy...yippee', but my feelings about that are no more the fault of the person documenting that time, place, those people, than my abhorrence at war photography showing horrendous violence or pictures of dead babies washing up on beaches.
Documenting what is happening does not make you complicit or approving of that which you are recording.
It might, if you start defending that which you are recording or actively promote what you are documenting, and that is worth discussing in an intelligent way and not snide jibes.
As for charity events, well, sometimes charity is more for the ego of those involved than the cause which may/may not receive any help.