"making only some software available in US" --- you slightly missed my point. I meant "software only available in US". That would be impossible to achieve with Sage, as Sage is open source. If you support Sage, you cannot control who gets it. (By the way, North Korea would also be able to use it!) The point, I believe, is to only support those projects which are under control and can be used for control. Maybe I am unfair to Simons. It is just hard for me to interpret this in any other way.
It is not only about software. Academia has other structures serving the same purpose.
Is your original post above meant to be sarcastic? I can't tell. A basic idea in scientific research (especially mathematics) is that we do NOT need "control mechanisms" like you describe that prevent research in order to avoid chaos. Instead, we have peer review, the scientific method, and rigorous proof (in mathematics). Everybody is welcome to try to prove mathematical theorems and do research, and the more widely we make the tools for doing so available, the better. In mathematics, when a group thinks they have solved an interesting problem, they write up the solution, make it available on the internet (e.g., on arxiv.org), and other researchers read it. If the group has correctly and deeply understood the solution to an important problem, then their work becomes more widely known and everybody benefits. I see absolutely no scientific benefit to restricting who has access to mathematical software, mathematics papers, books, etc. And definitely no benefit to making such tools closed source, thus restricting how they can use that software. One of my inspirations for starting Sage was watching a young Manjul Bharghava (who just won a Fields Medal recently, by the way) give a talk in which he explained how his research had been severely frustrated by Magma being closed source, so he couldn't modify it to do what he wanted.
Dear William, thank you for your great work! My post was sarcastic. I completely agree with what you wrote in your comment. But I do believe that my guess about why your proposal was rejected is partially correct.