First, Biden is not senile- so much for your juvenile insult.

Second, there is longstanding international norm against deliberately targeting foreign heads of state- so at least Russia got this one right for a change.

Third, how could the visit be "an insult to Russian sovereignty" since Ukraine is a sovereign nation itself? THe only reason would be that that view- that it is an insult- is because Russia views Ukraine as part of the Russian empire which Putin is trying to resurrect- thus confirming Russia's motives are not about Russian sovereignty, but conquest- just like in Chechnya, Georgia and Crimea