If I have a rabbi? You sure get mean when you disagree with someone. I actually asked the Rov of my shul (who is not a Religious Zionist) and he told me that many have asked the question and he personally does not have a firm grasp of what R’ Moshe meant. The only comparison he could bring is the opinion of the Gra that you get a mitzvah every time you eat matzah over Pesach but it’s not a chiyuv… but even that concept he doesn’t really understand.
And it is not worse than it was at that time. People died by the droves trying to travel from Europe to Israel by horse and buggy or however they travelled. How many Nefesh BNEfesh fatalities are there? There were crusades and wars that killed many, not to mention the lack of food and infrastructure in the Land of Israel during the Middle Ages. You may need to relearn history if you think EY was safer in the 1300s than it is today.
And I don’t know if it’s definitely worse now than it was when R’ Moshe wrote the teshuvah. But even if it is, you can’t assume he would say it’s assur to go nowadays because it’s too dangerous.