Does the fact that he could have the same low, with or without the set figure into your analysis, or do you think that just cancels out in each example?

I think the 5% figure for him betting on the river (after I check) with a worse hand is very, very low. I would put it as more like 20%.

Conversely, I think the 10% figure for him calling with a worse had is high by comparison to the above.

What makes you think someone is twice as likely to call with a worse hand there rather than bet if it is checked? That does not jibe with my experience at all.
I would say that just the opposite is true. I think an aggressive player that made such a big move is much more likely to bet there after a check if that is the only way they can take down a huge pot. They are getting great odds there.