This is probably just one of SourceForge's lawyer's overzealous misinterpretation of the law. (That's what lawyers are paid to do, of course.)
My question is, is SourceForge really "exporting" anything? Last time I checked how the Internet worked, SourceForge sent the packets to its ISP, and the ISP handled it from there. (Repeat until the packets are at their destination.)
(If the law says, "you must not transmit a packet addressed to a host in <list of countries>", then I guess that makes sense. But I have a feeling there is no such wording.)
Anyway, people in those countries should definitely be using Tor. So this will just remind them of that.