It was IT's problem before this person ever came along. That's the whole point.
A few quick questions:
1. Are you capable of implementing an IT infrastructure where it is impossible for a user to lose mission critical data? If not, then you're incompetent. Move along, please.
2. Are you willing to implement an IT infrastructure where it is impossible for a user to lose mission critical data? If not, then you're insubordinate. Move along, please.
3. Is it possible for a user to lose mission critical using an IT infrastructure that you have implemented and administer? If so, then you have a problem. Fix it.
Again, in an institutional environment, it is not the user's responsibility to safeguard mission critical data. By definition, this is one of the primary responsibilities of IT.
(Here's a hint: Mission critical data ever on a c: drive = IT failure)
I'm sick of this attitude of ...
And your customers are sick of your attitude. Thanks for demonstrating my point far more effectively that I could ever verbalize it.