I'm not sure I credit there being a difference that matters between "generality and unopinionated design" and "designed for AAA workflows".
When we say software's "unopinionated," this means much the same thing as when a person's like that: it goes with the flow. In game engines, that means an engine that uses the design philosophies already present in other game engines -- but the ones that the creators worked with, specifically, which means no Clickteam, and no Zillions, though both existed when Polycode was being developed. Ivan Safrin wanted a free and open alternative to Unity, which meant he wanted a game engine in the sense that Unity was a game engine.