Unsurprisingly even Apple laptops require ventilation; I thought it was common knowledge that you can easily destroy any laptop by running it on a soft, heat multiplying surface like a bedspread....
The way I read it: CPU gets hot, battery damage from overheating begins, computer shuts off. User turns it on again not knowing the state of the electronics inside. Possibly weakened or damaged electronics cause the battery to blow up.
Bad ventilation weakens electronics and continued use causes catastrophic failure. This is not new.
It's far more likely that a defect in the battery caused this. Perhaps the laptop tried to draw too much power from the battery, and it failed.
But if the battery creates the heat, the sensors for CPU temp will react too late.
The temperatures that start to increase failure rates for electronic components are far lower than those that trigger thermal runaway in Li-ion batteries. The least thermally stable Li-ion batteries, those with cobalt-based cathodes, are at risk of thermal runaway over 150C. I've never heard of poor cooling being the root cause of a laptop battery fire.