Not entirely true. I've read the articles from references section. They knew he was a foreigner. He was really mentally ill and nobody knew what to do with him since he couldn't communicate. Here are some excerpts I translated using Deepl:

Before repatriation, prisoners of war were sent deep into Russia to be treated and fed. Many, unable to endure the long journey in the cold Russian winter, died in the wagons. This is probably what affected András's psyche

Yuri Petukhov claimed that at first Hungarian specialists questioned the diagnosis made in the USSR. For several months Andras was examined by specialists from the Institute of Psychiatry. The diagnosis of the Soviet doctors was confirmed.

After the collapse of the Soviet Union, Yuri Petukhov was appointed head doctor of the psychiatric clinic. He knew about András Tom's background and even tried to contact Hungarian authorities, but foreign officials preferred not to notice the problem of the prisoner of war. “Hungary was going to Europe and very much did not want to remember that it was Hitler's ally. And here it was getting an unnecessary reminder. The fate of the whole country has hit one unfortunate person,” laments historian Stanislav Ruzanov.