At the height of the cold war, we had Russians in the US and it's not as though people went after them with pitchforks. We also had people like Bernie (not just him) visit the USSR and most weren't thrown in jail -some were, obviously, but the great majority were not. So I don't think that's exceptional because there is usually a defined context for hostile action to take place. Even when you have sworn enemies who have plotted against a nation (or similar entity), it's not like they immediately go on to execute their plan. They set a target and go after that --often times you get accounts of that person being at most detached but often "they seemed friendly, I never imagined..." Basically if you don't get in the way of their plans, there is no reason to have you as collateral as you are not significant to their goal.