Mike is the archetypal nihilist (Sociopath or Loser), the other two would potentially be engaging in a Clueless interaction if Mike wasn't there, according to the Scott/Rao theory of jokes, you need 3 for a Loser joke.

The preceding banter seems to be more of a Loser Gametalk: no social status is at stake; it's irrelevant to their white-collar role. Mike's Straighttalk intervention is typical of a sociopath; the wall breaking joke is that these Losers don't know what his real job is. If they did, the pointless but playful debate would have died a violent death-- because it'd get too real

If these were Clueless middle managers debating their value to their company, it might even be out of character for Mike to notice them..