That's a very narrow and honestly quite bigoted view to have. Anyone can use whatever label feels most comfortable for them, and that includes transmascs who have previously lived years under the label of lesbian. Who are you to tell other people what label they are allowed to use, what they feel most comfortable with? I recommend reading up on gender theory, maybe that would broaden your horizons. I wish you a nice day and hope you can let go of the hate in your heart </3