I second seigneur's comments, plus I'll add these ones :
a) Why say that Feser's points are "ambiguous"? There's nothing ambiguous. The restriction of "potential" to "natural tendency" is a wrong move. Because it's where the "strong point" of the objection stands on, in the author's own words, "that we are NOT dealing with all logical possibilities concerning X". But this is expressly what Feser doesn't do.
a) Why using "sex change" as a critique? It's wrong. It's actually not possible to turn a boy into a woman. What he's doing is making a boy look like a woman. But that's something possible. We can slice through "Such a boy did NOT have “the potential to become a woman”, and yet he actually did become a woman, by means of surgery, hormone therapy, and psychological counseling." by two points, either by showing that the boy did have "the potential to become a woman", but the restriction of the critique makes it impossible (but then, it's not Feser's mistake, it's the author's); or by denying that "the potential to become a woman" is impossible.
There're a few more points to be said, but again, why is this critique interesting ? It muddles the waters.
God bless,
FSC