It's not excusable, but if MS does take any shots, it's probably only in response to, and not nearly as much, as Apple. Maybe the interview with Gates was on that very subject. If that's what they're discussing, it's not like the ad pot shots.
As far as that ad with the 6:00 pm thing, it seems wasted since 99.5% of people who see it will never get the joke and just think it means that they can spend time with family after work instead of dealing with computer related work/issues.
These pot shots Apple takes at MS is only exacerbated by the fact that they received financial help from MS 10 years ago, Jobs praised MS and said to everyone that this kind of back and forth between the 2 companies was history.
In thee end, Apple is just so darn good that it isn't even necessary!