Broken offline files - client-side cache is newer than server

Client has Win7 laptop, folder redirection for desktop and documents.  

Unbeknownst to anyone, his offline sync / sync center stopped and were disabled, but he is still using the client-side cached versions of his files.  
Because of this his files are as much as a year or more out of sync with what is stored on the server and the newer, more-valid files are on his laptop.

I am concerned (because it doesn't seem clearly documented anywhere I looked), that re-enabling offline files and re-establishing sync will result in his client-side cache being overlaid by the much older files in his user\home$\username folder on the server.

Are my fears unfounded?  Will re-enabling offline files cause the newer files in his client-side cache to win the argument and bring his redirected server-based folder up to date with what's in client-side cache?  Or will it clear the client-side cache and load all the old versions of the flile, wiping out over a year's worth of work?