I'd really love to see the issue resolved.
It's quite annoying if you build a new version to Hockeyapp, and it is directly deleted because it's an older "version". Why bother building an old version to hockey if it is deleted anyway?
Sorting by date would also be my suggestion (feels more correct), but of course having the option to choose which sorting is applied would be best!
My workaround for this issue:
Delete 1 version on Hockeyapp, so your new build will be placed last in the version history.
However, due to continues delivery we've got about 15 apps updated each 30 minutes (max 10 versions are saved). Manually deleting each of these, with the risk of having your new build being pushed away directly after an automatic build is pretty annoying..