Yes . That's a stretch. Bewitched was a typical 60s sitcom designed for the masses as a night-time tranquilizer so people could laugh, engage in a little fantasy, and forget the problems of the day. I'm sure it was a coincidence that these 3 actors were gay, and nobody was trying to make it an 'allegory.' There were many actors from that era who were in the closet and we now know were gay or bi- (Cary Grant, Rock Hudson, etc.) I was a student at UCLA in the late 60s-early 70s, and took a few theatre arts classes - many of my aspiring actor classmates were clearly gay, with one foot in the closet, and one foot out.
I recall watching Paul Lynde on Hollywood Squares over the years. I recall that by the late 70s or early 80s, he was making gay jokes about himself. So even though he may never have disclosed it explicitly, he was outing himself with a nod and a wink constantly. I remember thinking it was quite daring for that time, though it wouldn't be now, of course.