Preventing users from changing Definition Query

Hi all

I am using lyr files that include Definition Query to let the user add some part of existing layers to the map.
This is done mainly mosaic datasets that have some rasters that the user should not be able to see.
The problem is that smart user can just open layer properties and clear the Definition Query.
How can I prevent this?
Maybe class extension?, Change registry to drop this option from ArcMap? writing something in ArcMap extension?

Any ideas?
Thanks
Mody