Discrimination and bigotry aren't always the same thing, and so while sexual preference in and of itself constitutes "discrimination" (i.e. the mere preference of one thing over another), it is not bigotry (i.e. hatred or fear/phobia of the other thing).

I for one have always been attracted to females, and feel no obligation to explain or justify my preference, regardless of whatever activist scare words (such as "transphobia!") it incurs. By the same token, I also feel no impetus to demand the same explanation or justification from anyone else, including trans people.

What this article (and others like it) is pushing for is pansexuality, with the corollary (explicit or implicit) that any deviation from pansexuality is somehow a form of bigotry, and therefore deserving of public shaming, regardless of the lip service you pay to all of us being "the navigators of our own desire."

Ultimately, I indeed don't want to sleep with trans women because of their genitals, and I quite frankly do not care if you call it transphobia or not. Labels used by activists constitute a form of propaganda that, especially in cases like this, are designed to silence people, or at least make them hesitant to speak their truth.