To be fair I don’t think the issue is Grove Street Games. The AI-upscale texture work wasn’t even done by them - that was Technicolor, who Rockstar, as far as I know, still use to this day.
The issue was that Rockstar gave them a tiny budget, not a whole lot of time, and then moved the deadline forward six months when GTA V E&E got delayed. I think the scope for the project was fundamentally wrong as well, the games needed a lot more than a straightforward port onto Unreal Engine.