It's because they know that the conservatives in this country are fucking racists. Every race that isn't white knows very well just how fucking racist half this country really is.
citation needed. white people and asians get along well, and in china and japan asians consider themselves white.
-----
there's plenty of explanations that don't have to do with demagoguery
for example Asians are over represented in the university system, the university system is overwhelmingly liberal, having your training in a liberal environment during your idealism shaping years has a huge impact, if you don't believe that then the Jesuits and religious order training shows that to be an absolute truism.
Other explanations include the socialistic/communistic culture of Asians, they are much more used to ideas of central authoritarianism/socialism hive mind obedience including up to straight communism in their culture, considering Asians are very likely to stick within their cultural niche and network while they climb the social ladder this also has an effect.
Communistic countries also have an atheistic viewpoint, so a religious based party would also be off putting in that regard.
none of these things are "racism" and are more realistic explanations of reality because unless you haven't noticed Asian shop owners are some of the most racist people in america.
Jews also share similar demographics as Asians, in fact more extreme, and this is with republicans supporting Israel much more than democrats do, however Jews vote democrat, it's way more complicated than the narrative you are trying to portray, and most likely it's wrong to say it's racism that is the cause.