Yes, I think that if the race caller sees a horse leave the field, for whatever reason - PU, RO, F or any mix of vowels and consonants - it's right for all racegoers, wherever they are, to know their horse is out. It's also right to not surmise too much about the reason unless it's horribly clear, and then for the effect it might have on connections, not too much detail.
But the complaint here, by Ardross, was that the information about CAPTAIN KIRKTON came too late in the day. As I said, I don't think the race caller can announce 'the horse is dead' baldly over the tannoy, although presenters can find out the animal's fate and news can come through the tv services accordingly. After all, they're paid to do a post-racing wrap, which includes all the buzzed-in or beaten favourites, surprise wins, and should also include info on whether a horse is no longer with us for future racing.
I'm not sure how one could 'glamourise' horse deaths, though. They're pretty stark and if the viewer/racegoer can see a leg's gone, there's probably little point in saying too much. Although, of course, if it's an on-course death of a much-admired and top-rated horse, say like ONE MAN or BEST MATE dying in action, then some words need to be relayed to show the respect in which the horse was held. If that's 'glamourising' their deaths, then so be it.