I am also skeptical, though I am no expert. SNARK are zero-knowledge proofs, they are intended to give a proof that a result was computed correctly, not prevent an unwanted computation altogether.

The fact that you can decrypt after the time passed is of course the easy part, preventing decryption before then is the problem.

Yeah, there’s no telling how secure it is. Works, yes. Easily circumventable, maybe, maybe not. There’s a lot of math involved and I’m by no means an expert at any of it or guaranteed to have implemented everything correctly. For my personal purposes it’s 100% secure unless you know wtf you are looking at (much like a one-time-pad). Once the code and algorithms are published, it’s only secure until someone breaks it.