I didn't take it this way at all. Why can't "he's not the right fit" mean exactly that? People can be brilliant but just not right fit the operating processes and culture at a company. I didn't really read anything negative into it from either side.
Sure, you didn't but as you can see in this thread, it's trivially interpretable in lots of other ways. Which is exactly why it is usually not put that way. This doesn't seem like a complicated thing at all.
As another poster said, though, you're basically asking for more BS, wishy washy corporate-speak, wish is often what people on this forum rail against. Damned if you do, damned in you don't.
I'm not asking for anything. You were asking something and I tried to offer an explanation. The answer is mostly 'because lots of other people don't feel the same way as you on a (relatively minor and subjective) point of interpretation.' Applies just as well to your feelings about 'BS, wishy washy corporate-speak'.