Given that there are Gods here I assume these Great Spirits are actually just administrators for the elements and not incarnations of the source of the elements. If they were they would probably be able to cut off one's connection to mana entirely or issue element specific bans like not being able to store heat or absorb water.
Well I would assume to the spirits and the great spirits, spirit mages are basically like family since the spirits form contracts with them so hearing that that they are being used as bait to summons spirits for sacrifices would rightly piss him off