Leftists also feel they can control Islamists. They see them as just another pressure group to be subdued and paid off with government money. Ironically, both groups have collectivist, top-down, strong-man mentalities.
During WW2, the leftwing German National Socialist Workers Party (NAZI) partnered with leftwing islamists - both had similar enemies and end goals.
Except the ends are radically different. Islam will destroy the Left, but for now they’re partners in achieving a radically different end.