Does the attack by Russian rebels pose a problem for Ukraine?

Today's news reported that a military unit composed of Russian rebels from Ukraine crossed the border into Russia. The reason for the attack has been attributed to increased attacks on Ukraine by Russian forces. According to the Visegrad 24 channel, the attackers have threatened that "their goal is Moscow's Red Square."

This turn of events is not rational from the perspective of Ukraine or, especially, Western countries because Vladimir Putin could use it to legitimize Russian military operations in Ukraine and elsewhere. It is also important to remember the statement made by Kremlin spokesperson Dmitry Peskov in an interview with the US channel CNN: "If our country faces an existential threat, the (use of nuclear weapons) may be considered."

Of course, it is evident that a Russian military unit from Ukraine will never reach Red Square and, therefore, does not pose an "existential threat" to Putin or Russia itself. However, facts have never mattered in Putin's actions. Therefore, the border crossing that has occurred now could lead to at least nuclear threats against Ukraine.

Another unfortunate consequence for Ukrainians may be that public opinion in Western countries turns against assisting Ukraine. If this happens, Ukraine's received military aid may decrease, endangering the country's defense against Russian aggression.

Hence, President Zelensky's advisor's comment stating that Ukraine has nothing to do with the attacking unit is sensible. It remains to be seen whether it will be believed in Putin's administration or even in Western countries.

Of course, I hope that the advisor's statement about Ukraine's dissociation from the attack by the Russian unit holds true and is believed everywhere beyond Ukraine's borders. I also hope that neither of the unpleasant possibilities I mentioned earlier materializes. 

Instead, I hope that the Russians do not exploit the propaganda advantage offered to them and that Western countries perceive the Russian rebels' attack as a rebellion against Putin's regime. Unfortunately, the outcome does not depend on my earnest wish. And not even from the fact that crossing the border could still be a repetition of the shots fired at Mainila.

Previous thoughts on the same topic: 
Will China ally with Russia against Ukraine?
Did the Finnish Prime Minister promise Hornet fighter jets to Ukraine?
Incapable of learning but capable of genocide