I don't know why they did that, but I have done the exact same thing many years ago when my children were babies.
If you are visiting friends or family, space may be limited, especially if the house is small. You set the playpen up right before bed wherever there is space. Since no one is coming or going until morning, the entry space is convenient.
This family was visiting. they had four children with them. Space may very well have been at a premium.
You pushed a crib against a front door where a drug deal had occurred earlier?