The US won't extradite them, but that only helps while they stay in US ground. Their vacation choices are far more limited, and visiting Black Hat or the Chaos Communication Congress is out of the question.
It's unlikely for foreign governments to identify FBI individuals. Until the recent leaks "nobody" complained about NSA hacks let alone individual NSA agents. What makes you think it will be different when FBI leads the hacks?
So if they hack the Brazilian government, they're punished with poor vacation options? This is proportional?