Even though I identify myself as straight, my mom (who takes pride in being an LGBT-phobe) has accused me of being gay because my GF and I know many people at our school who identify themselves as LGBT.
Just because we know people who are LGBT does not mean we'll become bi ourselves. In fact, if my mom ever finds out about my GF, she will go crazy and demand everything about my GF from me.
As for the question, it's hard to say if someone with AS is more likely to be bisexual, but IMO, it would depend on how a person on the spectrum is raised. Given my upbringing in a Catholic household, I was taught that if a person identifies as gay, bi, or transgender, it should be considered a rejection of God, but IMO, that idea is just dumb.
In fact, my GF (who is also Catholic) and I often volunteer at LGBT-related events at our school whenever we get recruited to do so.
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Silly NTs, I have Aspergers, and having Aspergers is gr-r-reat!