I thought something like this could happen, I told a friend and he called me paranoid.
Anyways, since the end of last year I've been backing up my game once per month and the CDLD's every time I add new ones.
Today after the patch (that broke my game) I just replaced the game with the backup and ran steam without internet, all working.
With internet, steam will tell me "rocksmith cloud is out of date" but I won't try to fix it, I changed to "only update when I launch it".
If you don't have a backup, go with the beta fix and backup for later, it is not the best solution but I guess they won't be able to touch my game anymore.