Interesting question. It's a pity that the author only considers ways that cloned Neanderthals might be mentally inferior to us though. Given their larger brain size, it's conceivable that they could have had greater mental capacities but were out competed for other reasons. One of the linked articles mentions that Neanderthals took longer to develop (possibly due to their larger brain size) and this might have put them at a disadvantage. Perhaps homo sapiens were simply more aggressive?
Though I don't have a source to back this up, I really think that population densities were too low during those times for much Cro-Magnon-Neanderthal (funny how one's capitalized and the other isn't) interaction. That said, aggression would not have been enough for humans, especially since the Cro-Magnons were probably weaker physically.
There is always the possibility that there were changes in the environment that they couldn't cope with but our ancestors did. Longer childhoods could have been a hindrance.
As you know, a larger brain does not necessarily mean a higher intelligence. It could have evolved to simply create a higher volume-surface area ratio that helped preserve heat in their heads.
Neanderthals, if resurrected, may indeed be cleverer than us. But the fact that we're here and they're not suggests to me that we are probably cleverer.
An interesting hypothesis about Neanderthal brain size is that most of their behavior, including tool making, was hard wired in neurons rather than learned through intelligence and culture. Neanderthal tools and dwellings are identical across tens of thousands of years. Human tools vary a lot from culture to culture and across time even if function is unchanged, because of imperfect propagation across generations.
The idea is that the extra gray matter in a cloned Neanderthal's head would have him instinctively finding good stones to shape into tools in a specific way, even if nobody ever showed him how to do that.
