[rspeed]

The torch would, most likely, be for emergency methane venting. They had previously used a torch for burning gaseous methane during de-tanking, but have since switched to a condenser to cool it back to a liquid. There would essentially be no reason not to continue that practice, particularly when they'll have a nearly unlimited supply of liquid nitrogen.

[SergeAx]

I was writing about Lucy launch, which used Atlas V rocket.