Nope not acetylene
but close.......Blazer Big Shot
It isn't the heating to 400C that would cause problems - since even vaked you would likely notice that much additional time - unless you put torch to the heater core and let it sit by itself without actually holding the torch in hand.
But there have been a few times that even with it set in C that I've let my mind wander and pulled it away at 220C on a new fresh load after not intending to go past about 180C
I think that with it set in F for usual usage and in a vaked state of mind that if it accidentally was showing C that it would be quite easy to go over 220C BEFORE realizing what was happening and I believe that hitting temps of 260C before realizing your error is going to ruin your load and also damage the silicone.
In the end ......temperature is temperature but I still like the idea of heating in C so that it would be easier to avoid the kind of situation that I described.
But I do understand the resistance to progress and joining the rest of the world in a modern metric measurement system such as metric SI units