The two reasons the author lists for not sharing their source code now were both true pre-AI. Open sourcing allowed others to review your software for their own nefarious purposes and (as anyone who has ever maintained a reasonably popular repo knows) results in a lot of PRs that may be of low quality.

I contribute to open source because open source is how I learned to do what I do and it only seems fair to give back. AI changes absolutely nothing about this for me.