"Racist" is a bit unfair. Yeah, he interned Japanese. But, if the very real concern is that J's could act as spies and saboteurs, what is a guy to do? It was the indefinite and without hearing that sucked -- and was unconscionable.
Have been watching the "WW2, WeekbyWeek" series. Highly recommend it. In practically every invasion of Imperial Japan troops (e.g., HongKong, Singapore, etc) there was extensive "betrayal" by resident J's . So, after a few of those surprises the next region on the path of attack started interning the J's. Probably didn't help a lot since Imperials were overwhelming.
That said, pretty much every country interned "natives" of enemy nations, Germans, Italians, J's, etc. Especially in areas labelled military zones -- ports and such. The US was stuck with a particular problem since we are so mobile. And, once the Aleutians were invaded, the west coast got real worried.

@bobbo666 Racist because it was based solely on race. Only one ethnic group (Japanese) based on the idiotic supposition that the loyalty of Nisei, although American citizens, would be for their parents' home country rather than their own.

@GaryMysels Your read past my point -- that no hearing was implemented in so many cases. Nisei ended up fighting, at least some did. Each person interned should have been interviewed and then dispositioned. Now, taking their holdings (land, shops, etc) was completely unconscionable.

As I also noted, other peoples were interned in other countries, too. Let's look at Germans. If expecting an imminent invasion as in England, would it have been wise to not take a real hard look at the ancestry of folks, at least in coastal regions? Isn't ancestry a powerful influence? Are we to say that is OK to ignore them since they are mostly white (I'm giving Jews a pass on this particular issue to avoid the Whoopi stupidity) and discriminating against whites is not racism? Or, whatever the latest silliness of the Progressives is going on about.

Race, color, ethnicity, etc is irrelevant in this context. Do they pose a threat? On the West coast, who poses the greatest threat? Why, those of Japanese ancestry. That they were born here is an additional consideration, but not a sole determinant. Look at child abuse and racism, it tends to follow what your parents say and do. On a risk of this scale, when other countries (and US) have been invaded with the help of J's residing in the invaded country, you have to be very careful.