I can't actually see the point of civilianising the position of Police Air Observer. Surely the point of civilianisation of any post is to save money & release officers back to front line positions. But by the time you look at the role & responsibility of the air observer and then allocate the task to the relavent pay scale, add weekend working and shift allowances, I doubt that you will have gained much. Then look at what you lose.
(1) Flexibility, If the machine is down for any reason you can temporarily post your officer to regular duties. You can't the civvy, they are on a contract & job description.
(2) Police Observers do arrest people! The aircraft is often first on scene & whilst it is not the ideal solution it sometimes does have to land and effect an arrest. ( Yes I know civvi's can be specials but it is not the same ).
(3) In public order situations it is not unusual for the local "Bronze" commander to hand effective control over to the aircraft ( Not so common now that downlink coverage is spreading). But will they have the same trust in the none Police observer, I doubt it!
So in short yes a Civvi can do the job, - a teeny bit cheaper, but given the cost of air support as a whole, and the loss of flexibility that might result, is it wise?