What determines whether we go to Friendship Gulag?

I've joined several games on the Roland rescue mission ("A Dam Fine Rescue"), and:

some times Roland is rescued in Friendship Gulag instead of in Bloodshot Ramparts

What determines this outcome? Is it randomized for each game? Does it involve a plot decision I missed?

A Dam Fine Rescue has two outcomes, based on your performance during the W4R-D3N fight.

Destroy W4R-D3N before the barge that Roland mentions arrives and picks the W4R-D3N up?

You will rescue Roland then and there and will not need to make a trip to the Friendship Gulag.

If you fail to do so, however...

You will need to make a detour to the Friendship Gulag to rescue him.

Note that the first outcome merely circumvents the requirement of the second outcome - the story will play out the same way once the requirements of the second outcome have been resolved if you have to do so.

(Note: I have actually never failed to destroy the W4R-D3N, so I can't say if there's extra story bits to the second outcome inside the spoiler location.)