First, this woman was dumb enough to attach her name to it. You incorporate and you have more protections (nonprofit entities are typically incorporated).

Second, idk all the ins and outs of this story in its entirety but there are at least two scenarios off the top of my head that would allow for the BLM org get away with it. The first is that the BLM ceo gets paid a fat salary. The irs is only going to investigate and sanction a nonprofit that is paying a ceo exorbitantly more than other CEOs of a similar sized nonprofit.

The other scenario is that the org bought the mansion and used it as a headquarters. This wouldn’t even raise any red flags since places need to have brick and mortar operations and there isn’t much difference between an expensive downtown Manhattan office and a mansion in price, but the location can be justified as it’s a grassroots movement and needs the space and to be need the suburbs.