The first aspect of this case is in England a police officer carries a firearm as a volunteer it is not part of a normal duty for a English Police officer.
As a firearms officer it is important that the officer is fully fit for duty and if they are not they should report it to a supervisor who can consider if the officer should undertake the duty.
My understanding in this case is the officer did not refuse to undertake the duty but brought to his supervisors attentions issues that caused him concern regarding his family.
The supervisor then considered the issues and made a jugement that it would be better if the officer did not undertake a specific duty.
Lets consider for one moment if there had been an incient with this officer on duty, what would certain factions of society and the media have made of it.
I consider the decison by the officer to raise the issue and the decision by the supervisor to remove the officer from the problem was a correct one, taking into account it in no way effected the policing of the premises in question.