I think it’s cool that your kid’s school has a expert in the absorbtion and opacity of various inks as a dean!
I’m sure in comes in quite handy for all those kids who want an 85 on a test instead of an 84 and will cheat to get it. 
I had a HS biology teacher that I argued with for about 45 minutes one class period because she made a minor math error on a Punnet Square. In the end we were discussing research she’d done as a graduate student at Vanderbilt with drosophila. What relevance this had to two-thirds not being three-fourths, I’m not sure.
I think the rescheduling sounds like someone looked over whatever they’re planning on dropping on you Monday and put a stop to it. They’re busy with their backroom dealings, I tell you… trying to win over the higher ups with their nefarious scheming.
I’d definitely ask what they think the motivation for all this deceit is. I’ve definitely had teachers that were incapable of dealing in a rational manner with being caught in a mistake by a student. I don’t think I’ve ever met a student that would go though this much trouble to change an 82 to an 84 (B to A, 98 to 100, maybe, but I don’t get the impression you’ve got the type of kid that’s worried about grades to that degree).