I have no idea why the dev is choosing to take a major hit in her reputation that she clearly worked pretty hard to build through great design and code, for no reason other than "I don't want to spin up a separate build".
And for what? If you're gonna burn through your company's rep, at least get something out of it. Contrast this to what another Indie Mac dev did when confronted with the same situation:
"Free updates to the 1.x product will continue for paid customers of TapeDeck. It means a bit of extra maintenance on my part, but I will do my best to keep my existing customers happy."