I had the same problem once. I sended a message to vb support and got almost identical answer in return. However I can understand that they cannot provide any "support" to older editions due to security and bla bla..
But I had luck that I save all my downloads regarding vb, so I found v2.2.9 and could return to old fashion. So my suggestion is: Always keep a copy of your vbulletin download, it only takes up ~500kb
/rjpa