In a few points NO it doesn't take away from gsp's win at all, and here's why.
kelvin is like 10 years younger than gsp,
gsp was out of action for like 4 years, kelvin did not take 4 years off.
gsp never fought at mw prior, kelvin has
kelvin is known for more stand up gsp isn't,
gsp told everyone after the fight the hole in bispings game, and that is catch him with a left because he has a hard time seeing from that side, better chance at landing something he doesn't react to right away.....So kelvin just followed gsp's recipe, copied it.
bisping fought not long ago how do we know if his brain internally has completly healed from his gsp fight, i recall gsp landing some good gnp on him....not taking away from kelvin but maybe bispings brain wasn't ready to take another good left hook so early resulting in a quicker finish.
gsp seemed to dominate bisping from start to finsih, he used different aspects of mma, and yes bisping cut him up from the bottom but in terms of the fight as a whole gsp pretty much controlled and dominated from begining to end, not only did he land the left and was able to do damage he finished with a sub choking bisping out cold....when you consider kelvins history and gsp's history and both there wins over bisipiong i don't think kelvins takes away from gsp's, if anything i'd say gsp's is more impressive since he had more stacked against him, time away, first time at mw, ring rust, jitters, ect.