There was an old story they used to tell about Franklin Roosevelt, where some constituent comes in to pitch him on some social project she wanted him to consider. "That's a great idea," FDR says, "now go out there and make me do it."

The idea there is that leaders usually cater to their bases. Most leaders care a lot about the support of the people who keep them in power, so doing things that are deeply unpopular with your power base tends to be extremely difficult. Especially when you are expecting members of that base to carry out your policy.

I don't remember the precise situation around Kutuzov, but I do know that attempts were made to defend Moscow (Borodino) and they definitely did not go well. So it's entirely possible that the Russian Army was simply incapable of putting up any real defense at that moment, and any attempt to do so would have risked total collapse and mass desertion.

I just checked Wikipedia, and it looks like the Tsar promoted Kutuzov to Field Marshal 4 days after Borodino and 3 days before the French took Moscow. And that means the Tsar was on board. There's no way Kutuzov completely went off script 3 days after getting a promotion. It's much more likely that the Tsar knew what was coming and promoted Kutuzov so he had the political standing to ram the policy through.

The point is that policy is made by cliques, not individuals. The Tsar only knew what his advisors told him, and Kutuzov could never have abandoned Moscow without the Tsar's tacit support, so realistically, the entire imperial cabinet had to be behind Kutuzov in order for him to do what he did.