Personally, this will give cops more of an unfair advantage when certain cop skins have reduced radar blips, more if they drive an unmarked/undercover police car. Another thing is that criminals frequently use /loc $cop more than looking at their radar due to the reduced cop blips for certain skins. Finally, Mike will need to make it evident that these civilians are undercover cops so that admins don't mistakenly punish them, for example, if they're in the same car with other cops.
Furthermore, this suggestion has been already been suggested before an rejected,
undercover cop