@HekazuAh well, I don't mean to make things too complicated. It's just that looking at the map, Orchid wouldn't have enough movement to get to the horsemen, especially since he has to protect Parum too. I figured it'd be a safer pet to just try and be on the defensive. But I do got a different idea, if it's doable.
Since Torus is a large size creature and Parum is a relatively smaller one, would it be possible for Orchid to simply let Torus carry Parum for now, and then Orchid can join Brannor in fending off the horsemen? I don't know what action depositing another living character would be, but doing this would avoid the headache of intercepting attacks.
An additional thing, I personally don't mind the whole "another creature readies their action to intercept the attack" even when applied to trash mobs for their boss. With the goblin example, I figured that would be rather par of course, as goblins may have been willingly or forcefully commanded to use their bodies as shields for their boss. It's just a matter of consent really; I can totally see soldiers doing something like this for their command, and goblins might if ordered but chances are they'll just attack. As for beasts and such, again it would be reliant on the beast themselves wanting to do so; a regular riding horse has no reason to try and intercept an attack for their rider since, like any beast, they do have a sense of self-preservation. A war trained mount however may have the discipline and training needed to understand how to defend their rider.
I don't see this as stepping on the toes of the protection fighting style since, as I mention, this takes a standard action as oppose to the protection fighting style reaction; an active attempt to defend someone as oppose to a more honed, reactionary ability to do so. If we had to make the comparison, Orchid using this action which he could spend to attack, defend himself, or do literally anything else, compared to a fighter with the protection fighting style who can still fight just as well as he could before, and should anyone try to harm any allies near him, he can spend his reaction to defend them. Not to mention the protection fighting style still differs and in a way is still better than what orchid is attempting: the protection fighting style grants disadvantage on the attack directed to allies potentially making it miss, whereas Orchid intercepting an attack will not affect the attack itself, or using Hekazu's version, may even increase the chances of hitting Orchid and doing more damage (If the advantage happens to be a crit).