If the user does not need to view the ladder logic, then all you need to do is to make a copy of your .PC6/PC7 file and then delete the entire program but keep all the I/O table and #Define table intact.
Your technician will still be able to go online monitoring to view the I/O status and View Variable screens to view all the data on the PLC.
You can set a create a user password on the TLServer with level 3 access (User level) and this user will not be able to change any variables inside the PLC nor reprogram the PLC.