Because many trans women see themselves as women (and no, this isn’t about self ID, I’m talking about trans women who are living as women be that pre or post op.)
I don’t particularly care if a gay man describes a vagina as revolting to him because gay men have a sexual preference for other men, and as such he’s not going to enter on to my sexual radar, iyswim? However, if you are living as a woman and your thought is to want to have relationships with other men or with gay women, then those describing you as revolting and sickening will feel different because they may have envisaged at some point having a relationship, and when these kinds of thoughts are put out there then it is hurtful and insulting to think that people have issue with that.
No. Fuck this shit.
Sexual orientation is a protected characteristic under the Equality Act
(1)Sexual orientation means a person's sexual orientation towards—
(a)persons of the same sex,
(b)persons of the opposite sex, or
(c)persons of either sex.
Sex. Not gender.
What is revolting and sickening is transactivists' demands that lesbians ignore their own sexual orientation and consider male people as potential partners. Lesbians are not there to validate transwomen's identities.
Sure it's hurtful if you are male and have decided you're a lesbian and the lesbians say no. Truth hurts sometimes.
If you don't want to hear the hurtful truth maybe don't pressurise lesbians to overcome their own legally protected boundaries.