After reading that many people come out only to be met with the statement, "You're just going through a phase" I find myself puzzled. People go through a lot of phases in terms of interests and hobbies and things and nobody dismisses those out of fear that they're just a phase. After all, if it's a phase then at some point it will stop. So what is it about the idea that someone's change in gender or orientation is a phase which means it must be stifled immediately? If it's a phase like any other, then it'll pan out in the same fashion and there's nothing really to worry about.
I agree with you. People have many different phases throughout their life that are not dismissed. Even being heterosexual and cisgender can be a phase as many people in our community identified that way at one point.
There are, I think, at least two reasons that this response can be given. One of those reasons, you've approached with the quote above. That is, if someone otherwise is good with you, this can be nothing more than their own denial kicking in to stifle the new reality. This is similar to the "stages of grief," which include denial. So in that case, it's not really about the person coming out at all. The statement about it being a "phase" is an open indication that the person has some trouble accepting this. Then, the second reason I can think of is in the case where it is not denial, but simply a put-down. In those cases, the person probably has a low opinion of the person coming out to begin with, and it's a way of dismissing, in a passive-aggressive fashion, the message being sent. I'm sure there are other reasons too. However, it's clear that it's not always an editorial comment about the person coming out, but instead it's a comment about the perceptions of the person responding. I think it's important to recognize those cases, where the communications ought to be kept open and continuing, as opposed to those where there isn't really any common ground. This applies to all situations, not just this one. Unfortunately, when we're emotionally involved in the subject it's very difficult to maintain that kind of objectivity.
This may be remote, but possibly this is somehow a remnant of (popular) thinking that began with Sigmund Freud saying that we pass through a homosexual-like phase at a certain young age when growing up.
