Time stamps are shown for both idea and comments on the individual entries (admittedly not on the list though)
The reason is briefly mentioned in article 119516
there seems to be a misunderstanding wrt the meaning of policy compliance or non-compliance. It does not signify the detection of an application.
Without going into the intricacies:
Provided the sub-estate user has sufficient rights and a Device Control policy is not assigned to groups outside this s/e the exemption can be made from the policy (if the conditions are met the 'Add exemption ..' button is active).
HTH for the moment