This post will show a way to keep RVT files from being able to be opened by double clicking them (do this on the client machines where you think run a high risk of causing an issue with this). This still will not prevent a "smart" user from dragging an RVT file onto their Revit shortcut on their desktop though, so be aware of that.
This can easily be setup in your IT Manager's Group Policy for all current users of a domain if you really want to enforce this for everyone... or maybe just to users within a certain group?... you get the idea.
You do NOT need admin privileges to make this adjustment because it will change the setting for the current user only.
Create a new txt file (or download mine) and place the following lines in it
(save it as "RevitFileOpenTroll.reg"):
Windows Registry Editor Version 5.00
@="BIM Model :P"
Double click this file on any machine that you want to make this change for. After running this registry updater, double clicking an RVT file will open the Autodesk Wiki page showing the proper method for opening a workshared model.
You can change the web site to one of your own if you like that tells the proper method for opening an RVT in your organization.