But it really wouldn't be any easier a win for the Grigori than for anyone that can build a pagan temple early on to set 1 priest specialist then use that first GP to build the first level of the alter, thus enabling a 2nd priest specialist. Add in anotyher priest specialist for any religious temples and it becomes easier and faster to get 6 GPs than it is for the 6 Adventures. Plus no need for a high level tech to upgrade those GPs before they can make those first 6 alter levels. Thus long before the Grigori can even get their special units to build the alters, some other, non-agnostic, civ could have been reaping the benefits of each of those 6 levels of the alter for quite a long time.
For example in a single player game as the Calabim, I was pumping out the GPs fast enough that I could research the required techs for the alter as well as other techs I needed for defense, my economy and to found all but one of the religions, and had enough GPs to get the alters built and all the special religious buildings built.
When you consider that each priest specialist is +3 GPP and the Grigori at most get +4 Adventurer GPP (1 from the capital, 2 from the adventurer guild and 1 from the Grigori Tavern), that's barely more than 1 specialist to gain GPs of any other type. Then considering it only takes a tier 2 tech, Mysticism, to build the pagan temple to get +3 GPP towards a prophet vs the 1 from the Grigori palace towards the Adventurers, But having to wait for a tier 4 tech for the grigori to build the adventurer's guild just to match the +3 a specialist gives
When ya look at it, letting the Grigori win via the alter is actually more difficult than anyone else doing so. Especially someone that can build all the religious temples and also has the philosophical trait and running pacifism. Sure, they will get their first Great Prophet about the time the Grigori get their 2nd Adventurer, but at this point they can start getting their GPs at least as fast as the Grigori can get adventurers by adding just 1 more priest specialist. Anyone going for the alter win is not going to run just 1 or 2 priest specialists, they're run as many as they can. I've had cities with more than 10 priest specialists.
In any case, I'd say the Grigori's method of building the first six levels of the alter was just as balanced as someone else running a specialist economy getting their alter built. So please put this back in.