Thank you for clarify. Not sure it covers everything, but it is simple. Thank you for sharing.
Yep, it's a draft. In addition, there will always be edge cases (e.g. casting spells while polymorphed).
I think this is a misconception, at least the way I understand Caps intent. I think the approach is a theoretical what if scenario. What if, you were writing the item interaction rules, how would you simply the writing/design/layout from what is printed in the PHB, sage advice, etc. He is not trying to add anything, but simply replace it.
I understand what he's trying to do (I think), I just disagree with the approach.
My preference would be
Repeat the rules in a consolidated manner so that you can read everything you need to know at a glance.
Add exceptions to the general rule.
So while I disagree with the weapon + shield only (and only for divine), I would have something like
summary
An exception to the rule is that if you are a divine caster using a weapon and a shield, you do not need a free hand to cast spells with somatic components.
That way if I have a decent understanding of the rules as listed elsewhere, I just glance through the summary and pay attention to the exception.
I also have a lot of sympathy for the people trying to write these rules. Writing this kind of stuff is really tough. There was an interview with Mr Hanselman a while back talking about the stealth rules and how much difficulty they had coming up with them. At one point he had a long detailed explanation of how they worked but they decided to throw them all out. It was a conscious decision on their part to leave the rules open for DMs to implement what worked best for their group.
I don't have a problem with the stealth rules as written, but I'm sure a lot of people would have preferred the detailed draft. If I wanted more of that crunchy detail spelled out for me, I'd probably be playing PathFinder.
I understand why they were trying to avoid duplicating the rules in the book (as I do with my summary) because of the tiny issues that could creep in. They're damned if they do, damned if they don't.