The existence of a sticker does not bind Harvard to anything. The LGF post (which you didn't originally link to directly; I had to go looking for it and I'm going to have to go shower again, now, but at least there's a meaningful link in your post) and comments fail to identify the "leftist group" responsible for the stickers or document their connection to Harvard in anything other than a geographic sense.

And the anti-intellectual, eliminationist "joking" at that site should embarass you for linking to it. Just because they "support" Israel doesn't mean they are decent people or true allies. Or right about anything.