Earlier quoted context omitted.
Spheres of influence are real. If Panama fell under a Russian-friendly government likely to stop US vessels going through the strait, would the US government just sit there, "respecting the democratic rights of the citizens of Panama"?
First of all, the Ukrainian government wasn't bent on stopping Russian anything, AFAIK. Second, I morally condemned many acts from the USA, like the second war in Iraq based on evidently fake accusations of weapons of mass destruction. So, why shouldn't I condemn even more baseless acts from Russia?
The (elected) government of Ukraine has just been deposed by street protests directed by right-wing extremists, half of the country is in shambles and the newly established government's first act was to attempt to abolish a language law aimed at favouring Russian-speaking minorities (not exactly a priority, when the economy is tanking and half your police force has been disbanded). It's reasonable to believe that gas pipelines are threatened and that a revolutionary government might choose not to respect previous agreements, since there is a fairly recent precedent (2009, iirc); also, it's fair to expect that such a ragtag of right-wing ideologues will likely make the life of Crimean-Russians very uncomfortable very quickly.
I personally don't see Putin's actions as "baseless" or irrational -- he's defending Russian interests that are clearly threatened. It's very simple and quite unsophisticated, but I don't see the moral scandal.