Is This Retired Firefighter's Claim About Putting Out a Car Fire Correct?

[u/AffableEffable]

Hi, I ran into this discussion on twitter, and most people in the comments were really mad at the ELBainter person (who claims to be a retired firefighter). I know absolutely nothing about any of this, so I was curious: are they right and the people there are just stupid, the opposite, or something in between?

[u/scubasteve528]

His take is correct.