I guess "secretly a little bisexual, but due to society's constraints will never consider or pursue a same-sex relationship" strikes me as heterosexual, not bisexual.

Sexuality is one of those areas where people want an abstract 'core' that is held separate and above environmental factors. For example a person may like to believe "I am the kind of person who could fall in love with a black man" and feel that never having fallen in love with a black man is a fact about their environment, not about their ability to love. I was wary of the difference you elucidated being something like "I like to believe that I am the kind of person who would be sexually attracted to both genders if only society was more permitting".