Dude… do you even read Maxx’s respond?
I also got 1 copy of Penquin as well, so I can confirmed it’s in the Tier Shop’s drop pool.
All 6 Guild War troops are exclusive to just Guild War reward and Tier Shops. I supposed it was intended, as you can actually use this troop in the event they drop. Those 6 Guild Guardians also drop in Elemental Invasion shop.
They will never be available in other key types and summoning stone. They used to be in summoning stone in the past, but they already fixed that.