There is no place in radical movements for anonymous and/or unsubstantiated allegations. Such allegations, whether from well-intentioned but misguided individuals or from state agents, have the effect of sowing distrust and division within our movements. They put the accused people in the impossible situation of responding to no one and nothing in particular, or risk seeming to admit guilt by refusing to reply.
Human nature is a bytch.
Unfortunately, as we can see with today's political discourse, if you make unsubstantiated claims enough on a large enough platform you will most certainly have an effect, even if your claims are debunked.