Fools miss opportunities, wise men seize them, and successful men create them. Opportunities are reserved only for those who are prepared.
Since it wanted to withdraw from France, the Tsarist Government naturally would not be held back by a mere "excuse."
If it wanted to withdraw without provoking a backlash from the Anti-French Alliance, there was only one path: war. Only if the Russian Empire went to war with a third country would the Tsarist Government have sufficient grounds to withdraw without being condemned by the other nations.
One look at the map made it clear that the Russian Empire did not have many neighbors left. Europe was full of hard bones, the British in South Asia were not easy to provoke, and the only easy target lay to the east.
Before the Tsarist Government could find an opportunity to manufacture a pretext for war, someone had delivered a handle right to its doorstep. A "declaration of war upon all nations" crossed the seas into Europe, and before the European countries could react, the Tsarist Government was the first to announce that it accepted the challenge.
One simply had to admire it. Plenty of people courted death, but never had anyone courted it so spectacularly.
Fortunately, it was only a farce. The declaration had merely circulated internally and had not been submitted to the ambassadors of the various countries, so it did not yet constitute a genuine declaration of war. Otherwise...
Whether it was legally valid or not did not matter. All the Russians wanted was an excuse to make a mountain out of a molehill, and the Far Eastern Empire had conveniently delivered one to their door.
Whether to fight, how exactly to fight, and how far to take the war—probably even the Tsarist Government itself had not figured