It should vent no problems it's a smok if any mod can do it that one can.
I'd be more perhaps worried about removing any sort of ventilation in the mod (although to be honest, you will still get it, (air I mean) and I've used silicone cases with no issues (although they did allow the vent holes exposure.)
The main thing I guess I'd worry about would be the insulative properties of the silicone, you won't feel batteries heating up as quickly if they start reaching an unsteady state.
This of course all presupposes that you WILL have a problem and provided you are using the appropriate batteries and handle them properly, the likelihood of trouble is pretty close to not much, even with a smok mod. The majority of battery events are user error, not silicone cases. I mean if they were THAT dangerous we'd be hearing about it already.
But, I'm glad you asked and just keep on with safe batteries and enjoy your case and etc.
Anna