Seeking reason grandfather detained in Seattle by immigration

I'd like to find out why my grandfather, Abraham Liwer, was detained for 2 months by US immigration, when he landed in Seattle (from Japan) on July 7, 1941.

I am researching my family’s escape from Poland during WWII. To summarise: my grandfather, Abraham Liwer, was the recipient of a Curaçao destination visa given to him by Consul Jan Zwartendijk in Kaunas, Lithuania, as well as a transit visa to Japan by Consul Chiune Sugihara. I recently learned that on his way to Vladivostok, my grandfather went to the American Embassy in Moscow and got a 30-day US transit visa.

My aunt and grandmother, Jadzia and Chawa Liwer, got Polish passports from the Polish embassy in Japan, and also two Canadian visas, with the help of Ambassador Tadeusz Romer. But I have no idea if my grandfather also got or maybe already had, a Polish passport. I have never found his documents.

I don’t know why my grandfather was allowed to board the Hie Maru ship with a 30-day US transit visa and his  Curaçao destination visa. Out of the 2,345 refugees who had these visas, none of them were allowed to continue from Japan using the so-called Curaçao visa. They all had to wait until they could get real destination visas, or they ended up in Shanghai for the duration of the war.

I don’t know why my grandfather got off the Hie Maru ship from Japan, in Seattle, on July 7, 1941, and was kept in immigration detention for two months. (His wife and daughter continued on to Seattle where they remained for two years until they could join my grandfather in NY.)

My Aunt Jadzia and grandmother Chawa Liwer were the only two Jews to get out of Siberia while the Soviets and Germans were allies. My family story goes like this: my grandfather bugged a woman commandant in Vladivostok for months until she relented and got permission for their release. I was told she did this because she had a crush on him. I would love to find out if there was a woman commandant working in a government office in Vladivostok with the power to do this.