"I can just as easily be good friends with both men and women, just like 'straights' can be good friends with the opposite sex without sexual tension." Yeah, but you've got to bear in mind, heterosexual culture really doesn't believe in straight men and women being friends without ending up together. The attitude that bisexuals might hit on all of their friends unfortunately isn't all that surprising, given that culture.
It's always incredible, though, how people just don't believe in bisexuals, asexuals, pansexuals, trans and nonbinary people, and so on. People have things so heavily dichotomized and cannot fathom that things are different than their expectations (in this case anything that's not either strictly heterosexual or strictly homosexual).