That would give it more legitimacy from an argumentive point in the action, but it wouldn't alter the after effects of doing so mate, countries would still move their reserves out of the countries involved - it's just common sense. Would you bank at a bank that has shown if it didn't like something you do it'll take all your savings and give them to a person you've wronged - (on a fundamental level it's similar).
As Tsubaki said it's about the trust in the reserve country and if that's eroded then you keep the reserve elsewhere.
I actually think Putin would be happy if it happened btw, as I still feel maybe the main goal of all this is on a geopolitical level to try break the current order. And at a 300bn price tag it'd be a cheap way to greatly further that goal.
As explained, this door has already been opened by the US with the Afghan central bank and in parallel with this action the demand for the dollar has gone through the roof. No one has backed off.
Humans understand that life comes with consequences and I am sure that when it comes to picking up the tab for Putins mess the fingers will quickly point at Russia. This would also act as a very serious deterent for any lunatic imperialist leaders looking at neighbours with greedy eyes, such as China and Taiwan.
It would be difficult for Russia for generations but this situation is of Russias making and is continuing because Russia will not stop their criminal behaviour.
If I came and burgled your house you would rightly want action against me, as would all right minded people.
If I commandeered the front two rooms of your house you'd want the powers that be to remove me, action against me and to see me punished.
More so if commandeered your rooms, robbed your possessions, raped your wife, killed your children etc.
That is what is happening but on a national level with Russia being the criminal. All right minded people would agree Russias actions are criminal and reprehensible, as the UN data indicates.