Interesting take - I agree with much of it, and disagree in other areas.
I wouldn't want the owner stepping in and holding top brass accountable mid-season, as a matter of routine. For the reason that Terry is an oil/business man, and not a man versed in the x's and o's of the game, nor with the front office of a football club. That is why he hires others who are experts in these fields to put the pieces in place to become a championship caliber club. And - for many years they were on that precipice.
As you note however - he did exactly this with the Sabres, and it was too much, too often. It put the players in a position to never be able to align themselves with coaches and systems. It also painted the Sabres, and rightfully so, as a last resort for GM's or head coaches to go to. Set up to fail.
I think the answer, as with most things, lies somewhere in the middle. There needs to be a post-season analysis by Terry of the philosophies instilled by Beane and McDermott, and an explanation as to why it seemingly shifted so abruptly starting with last year on offense.
I don't think fans would have a negative knee jerk reaction to any changes made to Beane or Mcdermott. There's been enough time on the docket for both. And the rest of the league similarly wouldn't have a negative reaction either. I hate to say it but it may be time. I hope I'm proven wrong this year.