he's getting Rete to run as an emergent consequence of the sum-product algorithm.

Say what? How does that work?

I was a bit disappointed, since (as far as I can tell) this work simply used Soar as an exotic programming language.

Pretty much all Soar work uses Soar as an exotic programming language. It's a production system. When I studied it, which admittedly was 18 years ago, it had no learning component beyond a mysterious, programmer-dependent "chunking". I would call it a cognitive infrastructure, that you can use to build a cognitive architecture.

Its claim to being a cognitive architecture relied (at least originally) largely on being able to model human performance time on different tasks. But any programming language will be able to do that, if the task naturally has some particular input-dependent runtime, and the task is described properly.

Soar has the problem that it's funded by the military, who want to use it in simulations eg JSAF; but they want untrained military personnel to be able to build things with it. They don't want a smarter AI as much as they want an easier-to-use AI.