A closed PR would have been even more damning for Microsoft. Especially given that Casey could have provided apples-apples benchmark results - not, what amounts to, a micro-benchmark.

From my perspective, there are two reasons why someone would build an entire project instead of opening a PR:

* Merely to be able to point and it and say, "see? see? I was right!" How obnoxiously childish.

* Implementing his ideas into a mature/non-greenfields codebase wasn't in-fact "extremely simple."