Look. I am all for ethical treatment of animals and ensuring their well being and safety. But PETA is a joke. No one takes them seriously and haven't for far too long because of asinine stuff like this. Riding a carousel animal does not equate "bad" treatment of actual real live animals.
I have been riding actual real live horses for basically my entire life at this point. Owned many and trained many. PETA would hate me for that. But if anyone who has spent the significant amount of time with real live horses the way I have, most of them actually ENJOY work and having a rider. It's a bonding activity and it gives them enrichment. Certain breeds, for goodness sakes, were specially bred to do a job. And believe me, a horse WILL tell you when they've had enough of something or they are unhappy. An ethical rider/owner will know this and take note.
I was riding real horses long before I was riding carousels. So PETA, do the math. Oh, that's right, that would require them to actually use logic!