Sorry but I'd almost believe you were trolling if you weren't a Mod.
If Infest is simply absorbed and PW:S stays up then the poor priests gets no Rapture proc. Making the poor priest go OOM (at some point).
Now if they downrank a bit then about 10 PW:S all break and the poor priest gets lots of mana back while still preventing all the Infests.
Downranking not to gimp yourself but to keep your mana up while still saving the raid.