If my son (or daughter) wants to pledge Alpha Phi Omega, I would tell them exactly what to expect, so that they will know what they are getting into. In any event, I would fully support their decision either way they decide to go. If my son decides to be a Gamma Sig, I'm disowning him (j/k)
If my son wanted to join an NPHC org other than Kappa, I would respect their decision, though I would ask why they were interested in another org.
If my son wanted to join an NIC org, I would be surprised yet in some ways proud that he was willing to affiliate with those whose social culture would probably be different from what he would most likely be accustomed to--IMHO that requires a certain degree of humility, but if he can identify with such individuals that he could call them brothers, who am I to deny his right to such joy in a bond of brotherhood? I would tell him to expect a social dynamic that is significantly different from that of an NPHC org, but if he can handle that, more power to him.