I think the question comes up because SMC also negates Mercy (which originally negated Achan's Sin).
However, I believe since SMC targets the abilities of both Mercy and Achan's Sin simultaneously, it does not "bring back" EI from the banish zone to be negated.
If something like Stiff Necked were played (instead of SMC) then Mercy would be negated meaning Achan's Sin would be working again and you would have SI once again (and EI would be back in play).