The reality is, if a person has been arrested and charged with a Sec 5 Public Order offence (case sent to court) then the conduct of the accused would have been very menacing, probably violent and pose a risk to the general public if not dealt with. Its worth noting that a person has to be warned re their behaviour and continue before they are arrested, they are usually fined at the station or Cautioned and only the more serious cases or serial offenders are actually sent to court. A custody Sgt certainly won't thank a Constable for arresting some one for Sec 5 and the offence requires a fair amount of process work etc, so officers would usually only arrest for this offence as a last resort.
Police Officers are conditioned to foul mouth violent fools but thats not the point and not really the point in the case heard by Judge Bean.
As New Judge states, why should anybody, including police officers be subjected to tirades of foul-mouthed abuse when trying to go about their lawful business. Perhaps a new simple law is now needed making it an offence to abuse a Public Official on duty etc.
The word 'insulting' in the act is currently under review but this is more to try and kerb the 'Lawfare' problems.