First thought that sprang to my mind when I read the headline, which wasn't addressed by reading the article, was "ebay ledger nano scam"[0]. I don't see how you can be sure strangers don't have copies of your keys. Unless the keys are generated and coins transferred automatically somehow when you first plug in the stick, which would be cool.

[0] https://cointelegraph.com/news/life-savings-stolen-from-seco...