Boeing Starting Engine No. 2 First?

[SixPin]

Historic

The main reason is HISTORIC.
“Back in the day” on the old piston props the crew would start No 2 while the Px were boarding on the left side door.
On turn around they would shut-down 1 to disembark and board the next load and keep 2 running. What’s more, the only reason 1 was shut down, was because it was too noisy for the Px, nothing to do with safety.
Ahhh! Those were the days!

How do I know? My dad used to fly them.