People call it a regiment because it is a regiment. Since September 17, 2014.
English language Wikipedos and most Western journos and American politicians and others have insisted on calling them a battalion (and a "militia" which they also aren't), but even the Russian Wikipedia article title is "Azov (polk)" that is Azov (regiment): https://ru.wikipedia.org/wiki/Азов_(полк)
People call it a regiment because it is a regiment. Since September 17, 2014.
English language Wikipedos and most Western journos and American politicians and others have insisted on calling them a battalion (and a "militia" which they also aren't), but even the Russian Wikipedia article title is "Azov (polk)" that is Azov (regiment): https://ru.wikipedia.org/wiki/Азов_(полк)