This is kind of cidicolous, if one of my people would tell me he can't help me to fight those two WRF Wraiths trying to kill me, he won't be a faction member much longer.
The others are right, being in different (and hostile) factions adds to the fun and diversity we have in discovery, and denying this to people who are interested in WRF is kind of rude and certainly won't attract many people to join.