Alternatively The Arimaspi could be ancestors to the Goats, similar to how (in descending order of generations) the Orcs, the Ogres, the Ogron, the Gronnlings, the Gronn, the Magnaron, and the extinct Colossals are all descendants of the singular elemental giant known as Grond in Warlords of Draenor .

I like the “proven wrong” tag, there

@sonicfan  
G1 Tirek was never able to absorb magic.

@Backgroundpony  
Tirek wasn’t redesigned so much as reused. He was a centaur in G1, he was able to absorb and release magic at will. His slight cosmetic alterations was done that even in spite of the alterations those familiar with the G1 Tirek would immediately recognize G4 Tirek by both appearance and behavior. Even G4 Scorpan’s appearance was such that those familiar with G1 Scorpan would immediately recognize him by his appearance. Therefore the Arimaspi are a different specie than whatever goat or ram that G1 Grogar is. Personally I think he’s a ram given the shape of his horns.

@sonicfan  
two words. Tirek redesign

No, he couldn’t because he has hooves and two eyes. Arimaspi only has one eye and has hands and fingers and is bipedal in body structure.

Plausible

@Background Pony #BF5D  
If they are related in someway to Grogar, then its as his soldiers. Makes more threatening troops than Troggles.

It fell into the ravine and died, there was a skull of it in the same episode;)

Now, that would not be a bad idea.

I can see them as his troops, replacing the Troggles.