I would have to say that this is absolutely great strategy by Sony.
Without Resistance 2, Gears and the 360 are at the TOP of everybody's mind going into the Holiday season. This gives Sony some needed mind-share at exactly the right time. Brilliant move I think. Please note, I don't know that there is huge overlap in the R2/LBP target markets so left that variable out. Of course the market could show post November that the combination was a much bigger driver of sales than Gears 2 alone on the 360.
I do however disagree with your assessment that a greatly reviewed R2 would adversely affect the Gears 2 review. Gears 2 is a third person shooter with multi-player modes based around 10 players. Resistance is a FPS who's trying to make a name for itself with large scale multi-player modes.
I think both these games could and should sink or swim completely on their own merits.
