SK didn't seem to be particularly harsh on Nintendo. To my recollection it was something along the lines of: we believe the future of gaming is in better stories and worlds and we need the power to express that. Nintendo's going in a different direction.
I can understand that too. Nintendo is still doing the epics, but cinematic experiences have never been Nintendo's focus. Hell, Nintendo still avoids voice acting and fully orchestrated soundtracks, stuff that became standard on PSone. I personally prefer Nintendo's approach to video games, but I appreciate Silicon Knights' ideas too, and so even if the company did return to Nintendo, I'm certain it would be on their own terms, as a third party. They don't want to make games for a casual audience, they want to make games for Sci-Fi/Fantasy nerds like me.
Edit: As for Factor 5, if they come back and offer a good game, I'll buy it. I don't really hold grudges.