Roentgens? That's like measuring fuel flow in hogsheads per fortnight. (All due deference to you folks in the U.K., but "fortnight" to us in the U.S. seems appropriately archaic.) And yeah, that probably means he's following the Blunder's lead and relying on stuff from the late 1950s.
Ha! I was trying to think of an archaic analogy, like doing eye surgery in fractions of a furlong, but I like yours better.
To him, "Can we agree that the data are correct?" is indistinguishable from questions of applicability. To him, "correct" includes "applicable," and it's a massive paradigm shift for him to believe that those may be two separate concepts.
It's really no different than his misunderstanding of the Saturn V issue. Once he gets it in his head that "Jay admits the plans were lost," there is no prying him loose from his simplistic understanding of how aerospace designs really are documented. In his mind any concession, no matter how carefully qualified or explained, validates his simplistic misunderstandings.
You've given an example and so has BPR. Here's mine: for over a year Adrian kept spamming me with, "Then you agree that NASA has altered photos." I repeatedly told him I was on to his game and I wasn't going to play it, because I knew he would completely ignore any qualifications I would make, and then he would go off bragging that "Apollo defender agrees that NASA altered the photographic record." Despite the number of times I told him I wasn't going to fall for his deceptive trick, he kept trying it. I likened it to a mother whose son is hiding behind the sofa:
Mom: Billy, I know you're behind the sofa.
<silence>
Mom: Billy, you can come out from behind the sofa now.
<silence>
Mom: Billy, I can see your feet. The game is over. Come out from behind the sofa.
<silence>
Mom: BILLY! That's enough! Get out from behind the sofa! NOW!
Billy: I'm not behind the sofa.