&quot;making only some software available in US&quot; --- you slightly missed my point. I meant &quot;software only available in US&quot;. 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.