“I’m all in favor of semantic markup, but if it will cause difficulty in a user agent, whether it’s a browser, a screen reader or anything else, the markup should be compromised to make the information easier to digest.”

This is a little too absolute for my taste. As with everything else in web design, it’s a trade-off: is the time spent on the workaround worthwhile? All else being equal, I’d pick the solution that satisfies the WCAG and minimizes the time spent on the problem. In this case it’s an alternative interface.

“It’s unfortunate that certain user agents incorrectly interpret semantics, but to claim that ‘any incompatibility with screen readers is an issue that the screen reader developers need to deal with’ is creating a scapegoat and avoids providing a solution.”

I’m not making them a scapegoat; it’s their product. They need to be held accountable; that’s why we have standards in the first place. And there is an interim solution: provide an alternative interface until the semantics are correctly interpreted by screen readers. It’s in the long-term interest of accessibility if designers and developers demand proper standards support from all user agents. There’s no reason why we can’t fight on two fronts at once.