Not really that upset about this one given the sort of person he was and how much his ideology wasn’t the ‘I have a dream’ side of things. Or so I have heard.
While on one hand we mythologize people, there are Great Men in history regardless if you subscribe to the historical notion or not.
The main issue is, like all people in the world, great or not, he wasn't perfect. Maybe he was far from it in your or other POVs but the point is these vandals didn't know or care about any nuance or context your alluding to.
The saw the statue of man who was known as a great Civil Rights Leader who died for his beliefs and were like, "Imma gonna steal them plaques honoring Black veterans and bits of the MLK statue for delicious meth money!" or something.
Unless of course it was some alt right Groypers or Black Hammer types that did this for spite and profit. In which case I have even less sympathy and more contempt for them.