There was a news article a day or two ago about a pensioner vandalising a statue of Thatcher. I feel the same way about this act as I did that - good on the perpetrator.
Unless a work of art is housed somewhere meant to cause reflection on all the actions a person took in their full context which includes making clear the problematic acts of the subject, they shouldn’t be somewhere clearly meant to commemorate them. And if they are, then they’re fair game.