He's been too naive and creduluous in judging a person based on limited information. His coding skills aren't in question — the software was fine while he was still in charge of it.

I suspect Dominic didn't see himself as the maintainer of the package, but as a maintainer of a copy of the package (like how git is designed to work). With this perspective, of course someone else can be a maintainer.

The problem is that NPM changed their upstream from Dominic to right9ctrl without checking. (Maybe because Dominic clicked a button — NPM is still responsible for accepting that decision or not.)