@PhDniX Isn't it some sort of begging the question (i.e. going in an argumentative circle)? It takes an accusative object (not a complement as a genitive), and therefore it retains "its verbal force," whatever that actually means, and to make the circle complete, if it still has this "verbal force" it takes an accusative. And thus for some reason, your counterexamples entail participles with some more "nominal force," and Thackston is still "right."
@PhDniX Okay, Thackston suggests that if the participal has some future sense, it has a "verbal force," interesting. So Thackston implies that, if it has a more present feel to it, it is more of a noun, right? I think I might have a closer look at it. 🧐 Thank you for mentioning some parts that would constitute counterexamples!