I disagree. Etymologically, "enshittification" is the ongoing transformation of something into shit. But here, GitHub is declining to make certain changes; it is expressly resisting transformation. At best you could argue it was already shit due to the lack of these specific enhancements that would deshittify it.

Doctorow, who first studied enshittification, identified three distinct phases of the process: "First, platforms are good to their users; then they abuse their users to make things better for their business customers; finally, they abuse those business customers to claw back all the value for themselves. Then, they die." I don't see how this applies to the specific set of declined enhancements.