I agree with the first part of this statement. That remco GT weight is lower than his default weight, and he climbs a tad better in his GT weight. He probably should not be in GT weight all year long, probably not healthy.
I think however Remco wins most TT these days regardless of shape. And whilst i think his natural weight is more suited for hilly classics, i would not say he is better at them. Unless future Remco has bad day in a GT when he enters it healthy, i think he can be equally good at GT. It just takes more prep. Reason being that only a few riders are truly capable of realistically winning a GT. Whereas a lot more riders are realisically capable of winning a classics.
He also has less chances at GT. He has only 1, max 2 chances a year at them. Classics he has more opportunities.