Is your script supposed to work with another kernel and set of patches ? about jetson-fan-ctl

[Pyrestone]

if you disabled the service then it is not running (i.e. does nothing and didn't cause your crash). If your pc still crashes after disabling the fan script then it is not the cause. Your custom kernel stuff sounds much more likely to cause that, so if I were you I'd look into that, or according driver issues.
The worst thing a python script can do is have an exception, which just stops the script and nothing more.