One point was more about how CBS would want to "pimp" (love that term) one of their shows...in fact, they have several successful shows on the daytime side. That doesn't necessarily mean the prime-time folks have a current need (and needs change--these things come and go).
CBS also has more hours, I believe, in summer devoted to their signature franchise in Big Brother than the other networks do with their summer reality shows (on a show by show basis at least). It eats up a good chunk of real estate, and their procedural & sitcom heavy schedule tends to generate fair numbers in repeats relative to the lower summer viewing levels making repeating them a cost-effective solution. This year they're down one scripted show with Zoo gone, but still have Salvation coming back. That might leave them with a little space to fill, but not as much as their fellow broadcasters.
ABC stumbled into success out of greater necessity. Their primetime schedule has been more of a mess, and they had fewer shows that repeated well (a few successful sitcoms and...not much else). Their Sunday nights were a particular problem in the regular season; the game shows were a good fit for their needs for something--anything--to run, and paid off. Much the same for Fox last summer--their schedule had little that repeated well, so a couple of game shows and more reality filler was a decent band-aid.
If and when Big Brother finally goes away, CBS may find themselves with the bigger need. Sooner or later, the pendulum swings.
