For what it's worth for me, F1 is clearly a team sport (with hundreds of people beside the drivers contributing to the effort), the WDC is clearly the pinnacle of the sport and what every team is aiming for (yes I know some 'purists' will claim it's about the WCC, but it's not really), and opportunities to win a WDC can be rare. So when you have a chance at one, even if it's a slim chance, you should go all in to grab it.
So to me as soon as it became apparent the McLaren was up there with, or better than, the Red Bull, and that Lando had an outside shot at taking the WDC, McLaren should have gotten behind Lando's WDC challenge and started issuing team orders.
I think Piastri would have been ok with this, based on how phlegmatic he'd been about team orders, and receiving upgrades second, earlier in the season. One overtake doesn't change my mind on that.
We've seen how pressure being applied to the seemingly perfect Red Bull and Max Verstappen has seen them each make uncharacteristic mistakes. You reduce that points gap by 15 - 30%, so it's something like 46pts, as might have been possible if they'd issued orders already in Hungary and Italy, and the pressure on RB and Max is so much higher.
The one counter argument I think has some weight behind it is motivation for Piastri. There's no doubt he's driven better in the second third of the season than he did in the first third. Does that happen if he's told he's playing second fiddle the rest of the season at the halfway point? Him driving as well as he is, and being a threat to take points off Max even on days where the RB is competitive, is a big part of why Lando has a shot.
But overall I'd still be all for it. McLaren should put everything behind Lando and the shot he has. The last time they were in this position was, what, 14 years ago? Who knows when the next chance may come?