Sony doesn't care because Halo is over-rated (like many AAA titles these days, more hype than delivery). Furthermore, the titles that were outsold are every bit as good, if not better in many ways, than Halo 3. Such a stupid thing to chest-thump over anyway...who cares Microsoft, seriously? Inferiority complex much??
(And I'm hardly any kind of Sony fanboy or whatever, I'm primarily a PC gamer who has owned both a 360 in the past and very much enjoyed it and its games AND currently owns a PS3 and enjoys it and its games.)