With a little bit of pre-planning, couldn't you make this process fairly fool-proof?
Specifically:
1) Decide to only distribute binary CDs/DVDs of actual Fedora and Enterprise releases, not
(say) alpha and beta builds.
2) Generate *.iso files for the corresponding source CDs/DVDs up front.
3) Store the *.iso files on high-reliability storage (a properly backed-up RAID server or
something).
When somebody asks for source code, just grab and burn the appropriate *.iso.
Realistically, this would cost a week of engineering time to set up, and a few hundred dollars
a year in RAID drives and server administration. GPL 3b is pretty obnoxious in this
day-and-age, but it's not that huge a hassle for anybody with good long-term data storage.