a person's supposed to wear whatever feels comfortable. more than enough of cis people wear opposite sex clothes just because they like it better, so i see no reason why trans people shouldn't.
being trans has nothing to do with clothing, it's all about what the brain thinks the body should look like. i'm sure if pink skirts were reserved for men only, trans men would desperately want to wear one just to look more manly in their expression, but then again some might not actually like wearing too masculine clothing, and would shy away from them unless everybody told them men are suppose to wear those things to be man enough. in the end, clothing style are more of a signal to ones self and others what one really is, a try not to be mistaken for what one is not, a way to signal belonging to a specific group of people, a way to revolt against conformity, or simply personal taste (i like this one the most), and many others.
any reason for wearing or not wearing something is just as valid as the other, and most of them don't really have to do with one's gender or birth sex or wanted sex or...
i generally wear the first pieces of clothing that match at all. appearances don't matter to me beyond some sense of aesthetics. if it looks good on me, i should be allowed to wear it no matter if they to others signal identification with a group that people don't really expect me to belong to.