See below.
Sure. But if they insist upon rubles, then you're going to have to go get rubles, and all other things being equal that increases the demand of rubles. Exchange rate between other currencies and rubles tilts toward rubles being more valuable, or higher priced.
They are currently beating Ukraine to death, unprovoked. Asking whether a murderer has the right of self defense while he is murdering is . . . wrong. To say the least.
Your anarchism is obstructing your vision.
Maybe people are 'loading up' in case Russia goes through with their threat and without rubles they won't get any Russian LNG or crude. Maybe they're preparing for the worst.
Math.
If I have 20 grams of 100 USD notes (1gm each), and you have 31.3 grams of gold, would you trade me for it? Because everyone else would. Gold exchange rate currently 1933 USD per troy ounce. That's 20 grams of money for 31 grams of gold. Worth more than their weight in gold.
If and when the price of gold goes to 3200 USD per ounce then we're at equality, weight-for-weight, gram-for-gram. Of course there's nothing stopping the Treasury from in the future issuing a 200 USD note or from reissuing the 500 USD note, and then we're just back to where money is once against worth more than its weight in gold.
Irrelevant to the above.