For your logic to make sense it would also need to follow that bisexuality is an inferior or less-vaild sexuality. At the very least, a "less sensical" one.
Absolutely not. That would be against the forum rules and ignoring our dear mod reminder.
To put it logically. If a companion backstory states it is A and playersexual makes it B there is a logical break.
A or B don't matter it is the break in the narrative that does. In that case removing the reference to A entirely would be better.
If you prefer consider a character as vegan and upon meeting you will move to a meat only diet. That's confusing.