Not sure if I'm misreading, but the OP's wording sounds like they're not already doing so. The sylphs have been summoning Ramuh for some time now. A faction of them broke off and summoned him and he immediately tempered a bunch of them to his will - hence why some of them are blue. The ones who still have their free will and still oppose the summoning of primals have fled to the safety of the Little Solace in the Black Shroud. The thing is, like Titan, Ramuh doesn't seem too interested in leaving his sanctuary just to wreak some havoc Garuda style. Something's going to need to piss him off, first...

Wonder who it'll be...