This isn't a particularly reliable calculation. You're estimating Yusheng's global average based on his PR average (using the numbers of the fastest solver in the world, no less), while those ratios are anything but predictable. I averaged (at the time of my PR average) sub-15, maybe 14.5-14.9. My PR average is 13.90. On the other hand, I have a friend who, at their first comp, averaged mid-high 20s and ended up with a 37 because of absolutely absurd stress levels. The reasoning you provided doesn't really seem convincing in the slightest.
In addition, what makes you think the ratio between PB single/average is consistent from a 7 second solver to a 14 second one? The faster you are, the closer you get to the theoretical minimum barrier (and the literal minimum of 0.00) of 3x3 times. Therefore, the smaller the gap between single and average. As you get faster, PBs have to be so insanely fast and lucky that it's much harder to improve them, which isn't as much the case for slower solvers.
You really don't provide any backing for your base assumptions, and you used a single cherry-picked example to find your ratios. And yes, it's "possible" that JDAW's sub-6's were/are legitimate. It's also "possible" to get a scramble with M' as the solution. And no, this post is not "proof that they're fake" or anything like that, just pointing out flaws in your reasoning.
I'm honestly 10x as sick of people trying to "stOp thE DraMA" than I am of people making bad analyses that "prOVe!!!1!" JDAW's legitimacy or lack thereof. One could argue that all of what we do is unnecessary, yet here we are enjoying the discussion nevertheless.