Its not unusual for a psychiatrist to have an opinion over a decision like breast reduction surgery. For gender dysmorphia, standard of care is for a psychiatrist to get two other letters of referral from a T and clinical psych.

It sounds like your psychologist perhaps considers that body dysmorphia is involved, and that the surgery is part of a bigger issue for you. He definitely could have put it in a more delicate fashion.

For what its worth though, psychological issues surrounding decisions about surgery are precisely a psychiatrists business. That's something they are almost uniquely qualified to opine about.