Koltuv, it isn’t hateful to expose deviant beliefs, regardless of who holds them. A great deal of lubavitcher chasidim believe things about tzadikim and especially their rebbe that are undeniably heresy. It really doesn’t matter if that person has a job with a mainstream publisher of Torah literature, though I hope he is not counted among those who attribute Divinity to a rebbe.
A common trick that MO and chabad utilize to stifle dissent and critique is the charge of sinas chinam, baseless hatred.
It’s the accusation itself that’s baseless.