You just have to remind yourself WHY the valve was there in the first place..
A couple of people have had their legs scalded in the last few years. I heard one guy was giving someone a passenger lap on a track day when his went!
Thats true... But you can't get then anymore they are NLA...
So if there bust you have no choice but to change them!!!
the Heat would not be a cause of the blow.
The Matrix End tanks would blow , no doubt through age of matrix and or increase pressure on the track day when it happend inthe story.
Nearly every car I have owned either has a flap or leaver type matrix, flap type , coolant is flowed through the matrix at all times and the air flap direct the heat over the core when you want heat.
leaver type will only flow coolant through the matrix when you set it to hot, not one of them have ever had a bypass like the golf very strange.