From what I found, the term Sapiosexual is considered derogatory. Some people consider it condescending. Why would it be any different than thinking someone is attractive while someone else is not?
Of course it’s valid. I’m turned on by people who like intelligent conversation, who can geek out on their favorite fandom, who can discuss Yeats or quantum physics. It’s not pretentious, I just like people with similar interests to me. Maybe people are just put off by the 6 syllables. Is it better if I just say geeks and nerds are hot??