I loved Armariver too, as crazy about Armaturk and they were similar types.
I'm not going to get into the debate about the trainer as a big fan and I pretty much trust that he cares about the horses he has. Who knows maybe the jockey was supposed to be light on horse if he tired - but then jockeys have to worry about not riding out for best placing. It's a lottery.
So many diff ways to look at this issue. It is a hard decision for an owner to run a horse again so soon after a good run but often it does work out. It's a personal choice tho and I would not want one of mine to run so soon. But I know I would have a fight on my hands as those I share with have run and won in those circumstances.
Trainers of course give multiple entries and sometimes the decision is taken to take up more than one of them when orginally thought was the horse would go for one only. Some horses take their racing a lot better than others. I worry about mine, and often get the mickey taken out of me because of that. Especially as I am female and everyone thinks I am being 'cuddly furry'.
I think it works well with sprinters but in my own humble opinion I would feel uncomfortable running a longer distance horse so soon. There is even one high profile sprinter who runs too often for my liking.
All of us learn by trial and error and sadly it is the horse who suffers most.
Through losses like this trainers learn the risk and can better measure the whether to run or not. Sometimes it is just accident with no cause though. Due to the percieved risk, I can name two trainers who refuse to run their horses too often, Hughie Morrison and David Elsworth, both go for longeivity because they have seen good horses broken down from over campaign. You cannot take Dessie as a normal example of how David campaigns his, Des was an exception to everything. Both lose horses from their yards due to owners wanting to run more often.
Anyway, very sad loss of Armariver - and I know the connections will be gutted too. All of them.