Apart from giving them a feel of a power, what does the fact of closing a thread (whether legitimately or not) give to the mods? Do they have some karma incentive to do so?
There's no incentive in closing a question, other than helping the site reach it's goals, and the primary goal for any Stack Exchange site is useful, not interesting or popular (not that they are mutually exclusive, but also not to be confused).
This specific question was turning into crap fast, with answers like "Sounds like your friend is a bit of a dick. Noone wants to work for him." (since deleted). Closing it only prevents further answers, as it was obvious they were deteriorating. Still, the closure and any closure, is reversible, people always have the choice to vote to re-open if they feel the closure wasn't justified.