People combining caffeine and creatine is nothing new, pretty common in today's supplement market actually.

Think about all the preworkout supplements that are on the market, almost all of them contain caffeine and creatine. Of course the caffeine is added in there so you can "feel" their product working and in a lot of cases these companies would still put caffeine in there even if it had negative effects on creatine absorption.

I'm not saying your right or wrong on the point of dehydration, just pointing out that its probably not a big issue to worry about.