from wiki:
Internment was popular among many white farmers who resented the Japanese American farmers. “White American farmers admitted that their self-interest required removal of the Japanese.”[20] These individuals saw internment as a convenient means of uprooting their Japanese American competitors. Austin E. Anson, managing secretary of the Salinas Vegetable Grower-Shipper Association, told the Saturday Evening Post in 1942:
“We’re charged with wanting to get rid of the Japs for selfish reasons. We do. It’s a question of whether the white man lives on the Pacific Coast or the brown men. They came into this valley to work, and they stayed to take over... If all the Japs were removed tomorrow, we’d never miss them in two weeks, because the white farmers can take over and produce everything the Jap grows. And we do not want them back when the war ends, either.”[28]
That one blowhard in California shot his mouth off and was prejudiced and wants a land grab, doesn't imply motive to Congress. Show me the congressional discussions where land grabs for the white were presented as the main reason for internment and I'll consider them.
Regardless of that guy's comments, the Japanese attacked us. And then some Japanese Americans helped a Japanese airman in the Niihau Incident. It raises suspicion on the allegiance of all Japanese Americans.