It is irrational. Just because you believe that various forms of xenophobia (writ large) are “human nature” does not make them rational. Phobias are irrational (that is ‘without reason’) by definition, and attempting to redefine a phobia from a clinical diagnosis to a justification based on your perception that people are inherently prejudiced is itself irrational.

Racists use exactly the same arguments. Racists argue for ethnostates on the basis of segregation being natural. They globalize their experiences and prejudices as universal rather than swing them as maladaptive opinions fueled by a cultivated hatred and distrust.

People are more than welcome to participate in LGBT communities, but they should recognize that those people are, in fact, people. They should recognize that they may come across like that scene in Blast from the Past where Brendan Fraser says “Bless my stars, a negro!” if they’re going to be like that, but there’s a world of difference between an ignorant but well meaning person and someone who both has embraced and propounds phobic talking points.