My point being, if they're sneaking around behind the Empire's back then the "contingency" is obviously going to be something *for them*, not for anyone else. If it was a special commission for Sidious (which is what such a thing would be) then you can bet he'd made sure they had every resource they needed, and wouldn't saddle them with some bureaucrat of an Admiral. He hasn't and they are, ergo: probably not Snoke. It just doesn't fit.
Honestly at this point, who cares about Snoke? He's not interesting or important, or even really a character. He was/is/will be a meat puppet, and then a dead meat puppet. There's no mystery to unpack there, no depths to plumb, so I don't see why they'd bother setting up a multi-arc mystery explaining how he came to be. Sure this may be the first step along the road to the Empire's own strand-cast program that connects this to both the ST and 'The Mandalorian', but that's a footnote at best, not that point of the whole story. I mean Snoke has already been at the centre of one anti-climax, why go for an encore?