Fanon actually talks about the role that radicalized settlers can play in the decolonial struggle. The settler can smuggle weapons to the colonized or hide fugitives in her residence because she isn't going to be searched by the colonial occupation. Nothing to see here, just an ordinary French citizen!
Settlers is much more pessimistic, seeing settlers as inherently untrustworthy because of their material relation to colonialism. It essentially forecloses on the idea of settlers class traitors.