Interesting thread but two points I'd note:
1) I wonder where he is getting that data from? Because if it's FBref (which a lot of those twitter threads use) then it suffers from the small sample size issue as I think I'm right in saying they don't cover the Eredivisie, so the data would just be from CL games.
2) I wonder how true it is that aerial ability isn't something that can be developed? For example someone like Pau Torres (who we might similarly see as a excellent ball-playing but aerially weak CB), went from a 47.4% aerial duel win rate in 19/20 to 60.6% and 65.3% in the subsequent two years, a fairly substantial improvement. Which (I would guess) was the natural result of a young CB developing physically. At only 20 years old I would expect Timber to be able to improve somewhat for the same reason, especially if greater emphasis was placed on that aspect of his game than has been the case at Ajax.