But Eric Szmanda himself made note that some fans felt alienated when the show went the GSR route.
When did Eric Szmanda say that? If you're referring to the Monte Carlo interview, what he said was that generally amping up the emphasis on characters' personal lives was the problem. While GSR played a big part in that, it didn't comprise all of it. His comment, IMO, spoke more to the issue of science vs. character drama/development, not GSR vs not GSR.
And as for Grave Danger, the finales always get higher numbers (though I'm not sure about this season's epically bad one), especially when a team member is in danger. Judging by this board, Sara seems to be one of the most disliked characters, but 'Living Doll' and 'Dead Doll' still drew high ratings. Warrick has been quite possibly the most under-utilized character in the franchise and, judging by this board again as well as by FFnet, he seems to have the least fans, out of all the series regular CSIs. 'For Warrick' still drew in the viewers. 'Grave Danger' was an episode unlike any other on CSI, seemingly due in large part to Quentin Tarantino and tptb. Figure that in, on top of the popularity of the CSI-in-peril angle, and I really don't think you can make the argument that Nick's character was the cause of the ratings.