these radiant heat panels come in different power ratings.

its safer when you only get the amount of watt you actually need, and not one that is rated much higher. with 160 watts, at full power you could probarbly cook some eggs. 40 watts is safer and may just be enough.

two reasons, why an actual fire is unlikely: it has a thermal safety fuse that will blow if temps get too hot. it will still get hot enough to burn your snake before the fuse blows, and the unit wont work unless you replace the fuse if its blown.

also you must use a thermostat with any of these anyway. the thermostat keeps it at the right temperature and will switch it on and off, a good thermostat will even run them proportionally. meaning a good thermostat can run a 40 watt heat panel at 10 watt or 15 watt or whatever is needed. heck, some thermostats are good enough that you could run a 1000+ watt oven or cooking plate at a precise low temperature.

so you have one safety, a good thermostat, to keep your snake safe, and a second independent line of defense, to keep plastic from melting and to prevent fire or smoke.