Absolutely I would affirm anyone's right to construct hir gender identity in the most meaningful way to hir. If that means ze identifies as wholly male or wholly female, then I would accept that and support it. I think it's reasonable to argue that men have feminine traits and women masculine ones, but that doesn't mean they're not still definately men and definately women.
In fact I think it's part of my "job" as a 3rd-gendered person to offer such affirmation since the existance of androgynes is sometimes co-opted by transphobes who point to us and say "oh, look at this person over here--ze doesn't identify as hir assigned gender, but ze hasn't transitioned or had any medical gender confirmation, so binary transfolk must not need it either."