I don’t know about that, but I’d assume he reconned the place.
If he blocked or chained the alley exits and then just dumped a bucket of gasoline into the entrance vestibule, he would have killed 300 instead of 50.
https://en.wikipedia.org/wiki/Happy_Land_fire
The Happy Land fire was an arson fire that killed 87 people trapped in an unlicensed social club named “Happy Land”, at 1959 Southern Boulevard in the West Farms section of the Bronx in New York City on March 25, 1990. Most of the victims were young Hondurans celebrating Carnival,[1] largely drawn from members of the local Garifuna American community.[2][3] Unemployed Cuban refugee Julio González, whose former girlfriend was employed at the club, was arrested soon afterward and ultimately convicted of arson and murder.
Obviously we need more laws against arson. Why haven’t we banned lighters, matches, accelerants?