That quote is from "Notes on the Next War: A Serious Topical Letter" which was published in Esquire in 1935 and was about war (based on his experience from WWI), not about surveillance or about standing up for democracy in times of peace.

FBI opened their file on Hemingway in 1942: https://vault.fbi.gov/ernest-miller-hemingway

Nobody in the US will "die like a dog" for supporting a presidential pardon of Snowden and Hemingway did not suggest that one should stay out of politics.