Does there need to be social immunity? No.
I have no use for it at all.
I simply think for the sake of completion one should think about what it should cost.
I'd argue it should cost the same as mental immunity.
Sanctaphrax: Would you be willing to include a link for this powers dicussion at the end of it's write up so people can see how we got here and can see the discussions on ACAEBG, Soulfire, Sacred Guardian, and social immunities?
The reason I think being immune to Sacred Guardian, ACAEBG, Soulfire, Righteousness, Holy Touch (if you have a power called There Is No Salvation - holy should likely hurt you). You get immunity to 5 powers bypass effects, some of which cost -1 through -5 refresh. Some argue Sacred Guardian should cost more. I think it merits -3 refresh, if the ability to bypass toughnesses ca cost from 1 to 5 points of refresh and the median is 3...that should be the cost in my mind.
I'd also like to agree with Becq one more time then hold my piece on the matter. (TINS and immunities to ACAEBG shouldn't exist) Powers that bypass toughnesses or satisfy catches generally ignore immunities and like effects. Why escalation occurs is with small rewording a new version of bypassing could exist specifically to include the new custom power. Since custom powers are allowed tehre is nothing in the rules barring errata based upon the gaming group's individual needs/tastes.