It sounds as though your council is over-using the power to exclude the press and public. The specific reasons permissible in this regard are listed in Schedule 12A of the Local Government Act 1972. Whatever reason is adopted, it must be clearly explained in the minutes.
On the face of it, if correspondence is open to misinterpretation, then care should be taken to ensure that it is fully and correctly explained in the meeting and the minutes thereof. If the community asset opportunity is subject to commercial confidentiality, perhaps because you are in competition with a neighbouring parish, there may be a case for exclusion of the press and public, but otherwise, it should be a public debate. Public support is normally a significant factor in the creation of community assets, so you'll struggle to show this if you hold your discussions behind closed doors.