So, it appears that if something is offensive, just complain and it will be removed regardless of whatever anybody else thinks.
If I were you TSM, I would complain to the PMC that I found the behaviour of whoever complained offensive and would like 'it' removed from the Mess forthwith. I find the ability of a small minority to force their views, values and opinions on the majority offensive. Will anybody do anything to stop it happening in future? I suspect not.
Racism doesn't have any place in the RAF, history however, does; if you don't like it, either man up or find a fluffier organisation to work for. I suggest the French government; they are very good at re-writing history to suit their own purposes.