For safety while handling, many explosives need both heat and pressure to explode. Famously, soldiers in Vietnam would burn C4 for heating water. However, explo

For safety while handling, many explosives need both heat and pressure to explode. Famously, soldiers in Vietnam would burn C4 for heating water. However, explosives tend to become more sensitive over time, and there's always a chance that the explosive filler in this bomb wasn't an insensitive explosive anyway. Given the chance of it exploding when burned versus exploding when jolted, it probably made sense to burn it in place