The test script is designed for v7+, I'm not sure that the warnings/errors that it detects will even be useful under PHP4 or UBB.threads6.
If he was on something more recent like v6.5.x I don't think that he'll need to even have a running forum as the UBB.threads7 importer I believe just accesses the database vs the active forum like in UBB.Classic...
I'm wondering if he could go through the v6.5 upgrade files and run the database queries manually then import that database to UBB.threads7...
Otherwise I'd generally run a local install of a WAMP that has PHP4 to upgrade the current forum to v6.5 so that it can be migrated.