Why would it be dangerous ? As I said, that officer needs to account for all his actions during working hours anyway, so there should never be a problem proving his/her innocence.
Or to put it another way: if an officer has, say an hour, on a working day in which (s)he can't account for his/her whereabouts and actions, wouldn't that be a good reason to suspect and investigate that officer ? What was he/she doing in that time, why did he/she feel the need to drop 'off the grid' for an hour ? If they have nothing to hide, then why would it be a problem ?