You can achieve market penetration while still selling less than your competitor. As we have seen last-gen, consoles can peacefully co-exist with healthy ecosystems.
And, just because the PS4 may be "winning" doesn't mean that Microsoft is at a disadvantage in terms of third-party relations. The PS3 did just fine with third-parties despite selling less than the Xbox 360 for years and years. The only "traction" that the Xbox One would get from beating the PS4 for one month is the reactions to the PR statement. It wouldn't make a difference in Xbox One adoption.
PS3 had the advantage to be at least strong in huge parts of the world and thanks to that catch up WW. Xbox doesn't have this. All they have is US, maybe UK and that's nearly it. If they do not win there they not only never catch up but fall behind by huge amount.
I believe this really makes a difference for studios in deciding if it's worth to go the extra mile to produce for Xbox especially when some games that are not in the line of Halo, Gears or Forza flop on this platform, if some games are more for european or asian market, if some games are artsy-fartsy.
It's okay that you say they do not care about the PS4-Sales and only want to reach their sales targets. if they are doing this by bundling stuff and lowering price like crazy, only to get their sales numbers for the cost of losing a lot of money - fine.
but there
is a lot of psychology in economy, especially in such an emotional branch like gaming (that is already about winning/losing...). so even if Spencer says he doesn't care about winning - these are sour grapes. they and their PR machine need this win so much. and they will get it.
we will see what comes after that.