I'm trying to give an honest, non-offensive reply to the OP, so I hope you'll be charitable with what I'm about to say.
I think I find myself in the camp of transgenderism not being a mental illness. It's kind of blurry to me, but I certainly understand the difference between gender disphoria and transgenderism.
But I don't see how transgenderism has been empirically or scientifically demonstrated to not be a mental illness. So far as I can tell, this is an impossible endeavor. What it really seems like is that the commonly accepted stance is a philosophical position, based on definitions. In fine, what I'm suggesting is that the way you define certain words and how you think about things in general (e.g. metaphysics/ontology) will ultimately determine your position on this topic- not any empirical evidence.
To suggest otherwise seems to be unsubstantiated, or a mischaracterization of the issue (read: debate). To insist that the other side is necessarily engaging in hate speech and that there will be repercussions for sharing their views (even if well articulated) is essentially censorship and promoting an ideology dangerously close to the untenable scientism. To be clear, if someone is just promoting hate speech, that's one thing (e.g. "I hate transgendered people," "we should kill all transgendered people," "transgendered people deserve to burn in hell," "$#@% transgendered people" etc.) but if they're actually promoting
reasonable
counterarguments (because it's a philosophical issue, not one of empirical inquiry), why should they be censored?
For example, virtue ethics- a certainly viable and acceptable normative ethical position- is based on what Aristotle referred to as ergon and arete.
To keep this short, he basically argues that what is good for a being is its properly functioning as the being that it is. This extends to not only beings, but artifacts as well.
A knife's function is to cut things. What makes a good knife good is not that its handle can be used to hammer a nail, or that one can see oneself in the reflection of the blade- rather, it's that the knife can cut things well.
A big question is whether or not we can apply this to human beings. Aristotle argues that human beings do have a certain capacity, i.e, rationality. Adult humans who are not exercising their rationality are considered not to be properly functioning. Some would argue that a human that chooses to remove their genitals or transition are not properly functioning as the rational being that they are.
While I'm not well-versed in this area of ethics, I know there are conservative defenders of extremely similar views who do a reasonably good job in defending their views intelligently.
I'm not saying they're right... but is it right to outright censor the opposition? That kind of scares me.