Either that or he has something to do with the possible upcoming sale/buy of twitter?
Also, as valuable as his presence is, I can't imagine a buyer of the size needed to buy Twitter would be like "we'll give you n Billion, but only if pmarca stays on point"
Not sure why he would delete the (public) history, though.
He was pretty notorious for blocking anyone with an opposing viewpoint on Twitter, so this seems in line with that.