Well, I definitely agree that a stock RSX-S and the 2006 Civic Si will not outrun the Cobalt SS/SC. But to say that with the support currently out there for that engine that a decently modded RSX-S/2006+ Civic Si won't beat a Cobalt SS/SC, I'll have to disagree.
But that AEM Acura RSX-S isn't that impressive either. Since it's AEM, they probably would not use the far superior Hondata K-Pro as AEM has their own ECU replacement. You have to realize AEM is going to be biased/limited to what parts they're putting on their car. It is advertisement afterall.
From what I can see, there's no mention of other 3rd party cams of any sort. The 2002+ Integra Type R comes with better cams and has 220 hp naturally aspirated. It's parts are easily interchangable with the RSX-S and has been done. There are even more aggressive cams out there for example Toda or Crowers.
As well, that RSX-S has been surpassed by so many on ClubRSX. I am not one of them...

The 1/4 mile times in that are also pretty sad. I've seen a lot of stock RSXes in the mid 14s.
I also have not yet brought into the equation forced induction. There are a lot of turbos/superchargers out there as well as FI cams. The other cams out there weren't suitable for FI because of excessive overlap.
Anyway, I'm just saying there's ALREADY a lot more aftermarket support out there for the RSX-S/2006+ Civic Si so I wouldn't expect someone's new Cobalt SS/SC to walk over any RSX-S he sees. A lot of them don't stay stock. The aftermarket might have a bit of catching up to do for the Cobalt. I say this because this thread's title mentions that the Ion Redline doesn't have a lot of support now and it's supposed to use the same engine (not saying there won't be a flood of people making stuff for it in the near future).
Also about the LSD, the 2006+ Civic Si should have one as well so it should have faster times than the RSX-S. Assuming the Civic Si uses the same engine mounts inserts as the RSX, you could shave off a bit more time with that too (no more wheel hop).