If opportunity has a cost, then that's a negative.

If your personal happiness benefits from you not playing checkers, then you have a negative cost to playing checkers, you aren't neutral.

1) I know that "anti-", particularly the antisexual movement, has more of a slant towards others than "a-", but there isn't a good alternative prefix that I can think of.

2) I am not redefining anyone's identity. I am asking people to more accurately communicate their own definition of their identity.