Well, both the X-Men and trans people so just happen to be a group of people largely shunned out and outcast from a large part of society for a trait they had no choice in having or not, and are seen as freaks of nature or worse by many others, so I can actually imagine the X-Men being sympathetic towards trans people in canon, really.

Sorry but your comment literally reminded of this:

In other words "people who only take stuff at the extreme surface level and fail to notice the messages being presented."