I watched that video a few times. Very slight difference when I had it on in the background. Still one has a brass nut, bone nut and something else he said. So they are all not identical and just changing the wood
Yes, he points that out... although he also specifically didn't play open to try to mitigate that issue. But yes, even just having a brass nut could change vibration transfer. But, you'll note his conclusion its not that any wood sounds a particularly predictable way (that's beyond the scope of a three neck test) but that different woods/necks will sound different.
IME, rosewood does generally sound warmer. And his thinner rosewood neck did sound in-between the other two, as we might expect if rosewood does absorb more high frequencies.
We need a 100 neck, side by side, rosewood vs. maple comparison with a machine plucking the strings to get even a moderately reliable scientific analysis.
Me, I'll go with what I hear... and play the guitar I like the sound and feel of.