It’s not a balance. About half the web still works from the Tor network. Also, Tor is not a DDoS threat to clearnet sites. There are only a few hundred exit nodes which work as a bottleneck to such attacks. The Tor network itself would suffer before a moderately competent target would fall.

A site calling itself "open data” should obviously be among the half of the world’s websites which function for Tor visitors.

And the fact that it cannot function even as an archive.org mirror, I must say it takes a special talent to be so incapable of being accessible. Most websites are reachable as archives.