...because none of those groups are Tankies and they are all unified against Tankies.
Tankies aren't socialists or communists (not that those two things are the same either). They are the purist ideologues of communism, where compromise is defeat. Rampant in telling you why you're wrong, and why only the purest form of communism will bring nirvana. All without understanding the consequences of what they propose.
Even the Communists don't want them on their side.
To say that Israelis aren't the only people needing protection.