I wonder if he ever considered moving to the UK, lots of cutting edge research and you get free public health care and very little gun crime. Also its in the EU (for now) so moving from Poland would have been easy.
As a matter of fact, I did, many years ago. Ultimately, I didn't go for it, but it was more a matter of circumstance than conviction. I think I would have been happy there.
The US is hardly the violent crime dystopia that some Europeans make it out to be (the overall crime stats don't really stand out compared to the rest of OECD), so this was never a compelling argument; healthcare, more so - although thankfully, the US is now getting a bit smarter about that, too.
But to be fair, the risk is not minuscule - for example the murder rate is 4-5 times higher in the US than it is in Europe. The only two times in my life I was close to being beaten up was during my few months visit to California.