Republicans would have a great case, if some Japanese citizens created sabotage on the West Coast airplane factories. Imagine the outcry by Republican because FDR did not protect those factories, and the Republicans would have a great case.
Instead some Japanese joined the American army and were seen as one of the best army units. But the big question is: how did Japanese-Americans vote for president even after the internment camps, Republican or Democratic?
The main reason they decided on internment was the fanatic patriotism Japanese in America expressed for the Japanese conquests in Asia in the preceding decades, the aid given a downed Japanese pilot in the attack on Hawaii, and the fact that for years the Imperial Japanese intelligence services had been trying to recruit American Japanese as spies and saboteurs for years before they attacked Pearl, and almost no one in the Japanese communities ever reported these attempts. Japanese communities in the U.S. had regular drives to collect money and goods to send to Japanese soldiers in Asia, same as our Red Cross did for our troops in wartime.
They were treated with kid gloves compared to any other peoples' treatments of similar populations in other countries, which is why we can safely assume only idiots and commies would spread the sort of nonsense about a handful of internment facilities here. They were also being attacked by other Asians, especially Philippino Americans, so their personal safety was also a factor.