It is cheaper to build on undeveloped sites - an airfield will fall into this category.
However under the definitions used, an airfield is a developed site - a "brown field" site as opposed to a "green field" site - central government planning policy guidance favours the development of "brown field" sites - hence any airfield is automatically under threat.
The funny thing is that if you want to develop and existing airfield as a fly in community much as one sees in the US or France - no chance.
I would think in this instance a fly in community with the big "flying properties arranged to provide some sound barrier to general housing could satisfy everyone. However, once a developer starts pumping the numbers into the development appraisal "all that, unused space" starts to look like such a "waste".
Generally, petitions do no good at all - good planning consultants/lawyers cost a lot of money - the best one can go is flight a delaying battle and hope that "the second best alternative" (there must be one) is promoted to "best location" if only because there a fewer objections. In this instance I am thinking this will be seen as a massive development spoiling someones rural/semi-rural idyll and so the "spoiling our village NIMBY brigade will be out in force.
Although I think it won't happen - pushing for development that retains light airplane use for recreation would be a solution. There are many examples of airfields next to residential property - Rochester springs to mind.
As an alternative - maybe use this loss of amenity to leverage another facility - e.g. the local authority endowing the other airfield on condition of no landing/tie down fees for singles under 1300kg in perpetuity. Here I enjoy such a facility at a what is a large international airport - not too many planes but those who have one do get a useful concession.
I would think that efforts to find a net benefit for everyone out of the situation may be a better use of people's talents, energy and money than locking horns on what sounds to be a losing battle for a facility that is past its prime and never likely to see the sort of capital expenditure to slow the decline yet alone see it reach a "high standard".