That does not seem to be supported by historically recorded activities. You would think that regardless of the total number if the government wanted to they could have interned at least as many (by number, if not percentage) Germans as Japanese, but the numbers are not even close.
During WW II roughly 120,000 Japanese and Japanese-Americans were interned or forcibly relocated (over 60% of those were US citizens, and because of the Immigration Act of 1924 that meant most were born in the US), out of the roughly 300,000 Japanese and Japanese-Americans population between Hawaii and the Mainland. This directly affected almost one third of all people of Japanese descent in the US.
And yet only about 11,500 Germans or German-Americans were interned (overwhelmingly German born), out of almost 6 million German, German-American, and German descended people in the US at the start of WW II. There were over 1.2 million German born people in the US in 1940. There were another roughly 5,000 Germans interned who were expelled from South America to the US after the start of WW II, so one might claim roughly 17,000 total. This 17,000 internees would have fit in just 1 of the 10 camps that held Japanese nationals and US citizen Japanese-Americans.
Remember that in the mid 1930's the American Nazi Party (organizations like Friends of New Germany and the German American Bund) had more than 10,000 members. In Feb 1939 the Nazi rally at Madison Square Garden was attended by about 20,000 people, and Hitlers activities were openly praised.
In other words, there were far more demonstrated supporters of Nazi Germany in the US than demonstrated supporters of Japanese aggression. And yet the Japanese were interned 10:1 compared to the Germans.
American military personnel of German descent were allowed to fight in Europe without general restriction, while American military persons of Japanese descent were generally not allowed to fight in the Pacific (there are a few exceptions, such as in certain military intelligence units). Japanese-Americans certainly did fight in WW II, but mostly in Europe.
T!