My reading is the author didn't do that, rather his/her employers configuration system had done so. Setting TMPDIR to /mnt/tmp seems also to come from that. I

My reading is the author didn't do that, rather his/her employers configuration system had done so. Setting TMPDIR to /mnt/tmp seems also to come from that. I would guess both were the result of someone who didn't really know what they were doing trying things until they found something that got what they needed to work, then pushed that out without understanding the broader implications.