I think that Prof K would probably argue that at no point is the Theravada Abhidhamma, it's commentaries, and sub-commentaries (etc.) is "reified". Though of course, much may hinge on what is actually meant by this term. However, look for his comments on the three types of definitions viz dhammas / sabhava, ie. agent (kattu-), instrument (karana-), and nature (bhava-). Not how these are developed over time.
My recently moved Blog, containing some of my writings on the Buddha Dhamma, as well as a number of translations from classical Buddhist texts and modern authors, liturgy, etc.: .