Why is the PKK not as legitimate as the Syrian Kurds or Iraqi Kurds?
Simply because PKK and PYD are marxist terrorists who represent themselves not kurds exactly as red khmers in Cambodia, Farc in Colombia or ETA in Spain.
Do you also back kurdish separatists in Syria and Iran?
Yes, I support Kurdish separatists in Syria, Iraq, Iran and Turkey. Nothing wrong with secular Marxist Kurds.
I have known only a few kurds in the USA-------none were "secular Marxists".
In fact------they were sunnis and a sprinkling of jews