The issue they're not talking about wrt swimming has to do with the swimming costume. Unfortunately, for a male who wears clothing cut for female bodies, most swimming costumes cut for women have no room to accommodate male genitalia. There is no possible way for a male to wear, say, a bikini bottom, without the difference between sex and gender made acutely clear to all observers. In similar articles I've read, THIS is the greater dilemma for TW.
They of course could wear the costumes fashioned for the modest, with skirted bottoms with hemline just above the knees, but for some reason no one ever thinks of that unsexy alternative.