I am not a lawyer. Still, my two cents are:
You didn't geobock the download or prompt for then user's address first in your scenario. So it may constitute export because it would be reasonable to assume that you clearly intended to make it available worldwide.
Phil Zimmerman was investigated for illegaly exporting munitions because he made PGP available via FTP. The case was settled, so I don't know whether this argument would ultimately have been successful.
Maybe some investigation worked this way, but to me it seems obvious twisting of supposed intention. If I don't geoblock, it is not necessarily because I want the thing to arrive somewhere. It can simply be, that I don't care who downloads it, or I don't want to waste my time with crazy laws, that I might not even know about. If Kiribati decides to have a new law, I probably won't even ever hear about it. Suddenly, me not knowing laws of another country, that don't even apply to me as citizen of my own country get construed into me "wanting to export"? Lol, what a silly line of thinking, which can only come from some people, who do everything to get to someone, including arguing in a completely twisted illogical way, and judges, who are removed from reality letting such a thing happen.
If we allow this shit to happen, be prepared for evolution deniers to push their nuts agenda through the same channels and similar. Suddenly, we won't find wikipedia articles any longer and suddenly having a blog about biology will lead to one being investigated.
This is how the UK interprets things, but they seem to be alone on this in the present day.
Wyoming just passed a bill explicitly refuting this interpretation, other states are working on their own bills, and there is even a federal bill in the early stages.
The only exception that the US has ever acknowledged to this is ITAR, which is what the PGP case was built around, but it failed as you mentioned. But non age verified OSes are obviously not munitions.