How else it is categorized probably depends on the categorizer's politics. That's not to say that all Republicans will deny the comment was ill-advised or that all Democrats will say it was. Partisanship may be a factor, but the aspect of politics most relevant in this case is race, not party.
Language can hurt.
It can and does communicate a lack of understanding about others. Our own words embarrass us sometimes by giving sounds and meaning either to what we really think or what we have not thought out. It is based on stereotyped speech patterns of Asian Americans. It offends because it demeans by generalizing about how they talk. But that isn't a reliable gauge of the matter, since senators know that the colleague who insults them on any given day may be the very one needed for support on an issue later on.