I was wondering if someone was going to call him on that. I’d like to think that the “gay to boot” was to emphasize or explain his failure or unwillingness to reproduce: “The Spanish ones kinda died out with Charles II, who was mentally-deficient and gay to boot.” (boling mine)
Being gay was common enough among royalty but it wouldn’t have been something that their parents celebrated, especially if it compromised their chance at reproduction (though there certainly were gay royals who managed to sire offspring). I’ve never heard that Carlos el Hechizado was gay, but my understanding was that he was mentally retarded and epileptic. Such things happen when you concentrate a gene pool too much.