While I agree with you, I think McLeish knows he is walking a tightrope. He was not a popular choice and it won't take very long before the wolves start circling if/when it starts going wrong. If he overplays his hand and the players push back he could find himself in a very precarious position.
I mentioned this on another thread (or maybe this one), but the manner of his appointment significantly weakened his authority which meant he wasn't able to crack the whip over the Mexico/Peru farce and also meant that the many knives that would have been out for him even if he had been first choice were getting sharpened on a daily basis.
I reckon McLeish handled that situation pretty well, seemed to get have the players on side and, even though we lost, managed to gain a lot more out of it than you'd have expected in the first place. All of that served to strengthen his position in general, but in particular it allowed him to say "well, look at x, y and z who have taken the opportunity" and use it as a bit of leverage over players who didn't go.
Factor in the win and very good performance against Albania (a game which, imo, was the real first step of his tenure) and I think he's absolutely entitled to play a bit of hard-ball at this point. No matter what he does some sections of the media and public won't take to him, so there's little point in him holding back; the knives are already out so he may as well do it his own way rather than pussyfooting around dicks like Griffiths. It's possible that he could overreach, as you say, but that's true of all managers.
It could all go tits up tomorrow, but as it stands I'm actually quite upbeat about our chances under McLeish. He wouldn't have been my pick but he's here now and I'm not overly upset about it at all.
In related news, I see that gormless tit Brown is piping up again: https://www.bbc.co.u...otball/45814174.