Not x aring/knowing it went negative is like saying contract size doesnt matter Lol i dont think he asked about the why which you are right on that part
Stop loss didn't work in this context. IF it did, there is no need to start this thread. Stop loss is the most basic risk management technique.
From what I understood, It was assumed that 0 was the floor, Hence no stop loss was used to limit risk. Not sure why it wouldn’t work. Because the broker rejects negative orders ? Change broker then.
Broker software got confused and refused to accept orders with -ve price. This happened even with reputable brokers like Interactive Brokers.