I wouldn't put silicone into the enclosure anywhere near within 24 hours of applying it. Partly because you don't want the snake smearing it around, not that that's a big issue, and mostly because it releases acetic acid (vinegar) while curing. The enclosure is by its nature and namesake enclosed, and if you want to imagine what it would be like, open a jar of vinegar and take a big sniff of acetic acid into your lungs. It will make you feel a bit irritated, but imagine being in a box with that and unable to escape.
In a situation like this I'd personally either just place it down on the floor of the enclosure and put the tile on top (a small snake shouldn't be able to move it and it shouldn't be a disaster if he somehow did) or put it underneath the glass, or you might think of something else. But, I personally would never use a glass enclosure for various reasons, and either way I'd just use this as an emergency fix while coming up with a more permanent solution.
In a situation like this I'd personally either just place it down on the floor of the enclosure and put the tile on top (a small snake shouldn't be able to move it and it shouldn't be a disaster if he somehow did) or put it underneath the glass, or you might think of something else. But, I personally would never use a glass enclosure for various reasons, and either way I'd just use this as an emergency fix while coming up with a more permanent solution.