Ok, I had a typo in the deployprobe.g filename.
But this is not gonna work anyway because of the following reasons.
M140 (without parameters) does NOT reactivate the heater. This probably is a bug.
The scripts are called at the very beginning and end of the mesh calibration. This is not what is needed for sensors of this type because the leveling will take a while and bed temperature drops quite a lot which will result in completely different offsets at the start and end. The heaters have to be turned off when the probe moves down (until it triggers) and back on, when the probe starts moving up again (right after triggering). So the bed heater would be shut off several times (at each probe position) for a second or so when the probe moves down and stay on for the rest of the time. This would keep the bed temperature relatively stable and allow precise mesh compensation.
The hotend still cannot be turned off and on again.