I would point out that "being opposed to sex-reassignment surgery" is not so much an opinion as it is an ideology. I suspect many safe spaces would be far more open to including people who subscribe to that ideology if those people entered those discussions with a willingness to learn, a desire to honestly explore the pros and cons of that surgery, and a desire to share their own experiences of gender while also learning about other experiences of gender.
That is not any easy thing to do and it is especially difficult to do for cisgender people who have little knowledge of the emotional land mines they can trigger by simply relying on the "common sense" they have learned over a lifetime. If there is an honest desire to be included in these discussions, I would highly recommend taking the time to listen and learn before you start sharing your viewpoint so you can understand the effects that your words will have.