Currently if you do not let your employees edit their “Prefer” and “Dislike” work time preferences then that whole section is hidden from their interface.
Note while you can restrict the employees from entering or changing their set ‘cannot work’ times, there really is no downside to letting them edit their own ‘prefer’ and ‘dislike’ time preferences, which then allows them to view all preferences.
This is because you can let your employees then maintain their own prefer / dislike information without you having to do it for them, and you can still control their ‘cannot work’ time information. If you like, “Prefer” and “Dislike” information can be ignored when manually assigning or using AutoFill if you like, or you could choose to factor it is when making assignments.
Only ‘cannot work’ is adhered to by AutoFill so there is no downside to letting employees set their prefer/dislike times themselves and that would also allow them to see preferences, including any ‘cannot work’ times you have entered for them (even though they cannot change that information).