I do think some measure of it would happen regardless, but if fewer people perpetuated the notion it would happen less. That said, and this responds to some of your points. I can't blame a woman who truly believed she was a lesbian and then suddenly finds out she's attracted to men too. No one can see or read the future, I can't judge her based on information she doesn't have.

I am talking about women in relationships with men calling themselves lesbians. Women who are actively looking for relationships with men calling themselves lesbians. That distinction is important and the one I'm talking about. I don't fault someone for being mistaken.

But just because someone can enter into a heteronormative relationship, doesn't mean they have, or that they will.

This is true, but the fact that they can is not worth nothing. It's worth talking about.

Also, closeted lesbians benefit from the assumption of straightness in the same way bisexual people do.

For the sake of discussion I'm leaving closeted women and those who don't know themselves yet out of it. That is a whole different discussion all together. And the presumption of heteronormativity doesn't really count for a lesbian in a relationship with a man the same way as a bisexual woman in a relationship with a man because she cannot be attracted to him and the relationship will cause a whole host of problems for her.

if she mentions a coincidental attraction to males, I don't demand she stop referring to herself as a lesbian

I'm not going to demand it of her either, and if she says she's sorting through it or just starting to feel that way I'll be there for her through it, but at the same time if she ultimately decides she does like men then yes I'll suggest she should identify as bisexual because that is what she is. There is nothing wrong with being bi, I kinda wonder why bi women want to call themselves lesbians so badly.