Well first of all, didn't Hinkie resign? Nonetheless, even if you believe he was fired, I don't see how that's silly. Hinkie did what he set out to do - give the team every possible chance to land stats via the draft. Thanks to phase 1 of the process, they now have oodles of valuable assets. Who knows if he's the right guy to handle the next phase.
It sounds like Hinkie resigned because they let him know they were bringing in people above him to basically do his job. At best, he was getting demoted, at worst, he would be made obsolete.
So, he wasn't fired, but he wasn't NOT fired.
As to the "who knows if he's the guy" thing, I just think if you hire a guy based on the strength of his vision for how to manage a rebuilding process, and he does a good job in the first phase of that plan -- in this case, acquire assets -- it behooves you to let him see out that plan.
It's like hiring a guy to completely renovate a piece of land and then firing him after he does the hard work of demolishing the existing building, leveling the ground, laying the foundation, and procuring all of the necessary building materials.
But perhaps his apparent failings in properly taking into account the human side of the business, and his disregard for the magnitude of problems caused by drafting multiple players at the same position, eroded their confidence that he would do a good enough job in turning the assets into a team.
I still would've just told him to hire some assistant GMs with more knowledge in those areas and allowed him to continue to architect the rebuild, but that's me.
I don't doubt that he has fans around the league for what he's done. He'll get hired on somewhere and probably get another shot at a GM job eventually.