I've been doing something even better than this for years using only Mistral 7b.
My local running Mistral 7b is a 100x better at modern JavaScript than any model on the market, mainly just from RAG on my own code samples.
That's basically what they are describing with "post-training", the TLDR is that code especially of a certain style is vastly simpler than written language.
You really don't need a huge model or data centers etc. you just need a small but good model like Mistral 7b and literally a few good samples.
But you guys keep doing you lol. A bunch of non-devs trying to solve code is pretty funny to watch.