In your question there is a false assumption that Russia in some way recognized the legitimacy of the declaration of independence of Kosovo. However, it's not the case. Your quote is the statement made by the Republic of Crimea. That was not a statement made by Russia. Whatever the reasoning was on the part of the Republic of Crimea, it DID NOT automatically reflect the reasoning on the part of Russia.
Russia refused to recognize the legitimacy of independence of Kosovo because Russia recognized the Constitution of Serbia, according to which Kosovo was an integral part of Serbia.
In the same manner, Russia agreed to recognize the legitimacy of independence of Crimea because Russia recognized the Constitution of Ukraine, according to which the state power in the country was by NO MEANS to be changed as a result of a revolution.
Since a revolution had taken place in Ukraine, the Constitution of Ukraine had been violated (and, in fact, the very State defined in the Constitution had, thus, stopped existing), and Crimea was not obliged to submit to the new government in Kiev, which, according to the Constitution, was, in fact, illegal. To stay submitted to that government would have been simply to support the violators of the Constitution of Ukraine. The only way not to do that (not to submit to Kiev) was to declare its independence. Hence, Crimea did that and Russia recognized that.