It's not my part of the country, but my previous involvement with Manston was as the CAA's aerodrome (safety regulation) inspector (along with about 30 other aerodromes in the southern part of England).
The MP and TDC do not seem to have a real grasp of the costs involved in running a viable airport, nor of the relatively meagre income a low-cost operator would generate for them; and the terminal is hardly a shoppers' paradise - won't sell many socks or ties there (even if the low-cost passengers were to materialise, they are notoriously stingy in aiport retail outlets).
Maybe they should splash out on an unbiased aviation consultant first. Someone who could spell out the costs involved with providing an ATS, along with operation and maintenance of the associated comms and navigation equipment. Then the operations staff for ensuring provision of a safe operating environment, inspecting and clearing operating surfaces, keeping the wildlife at bay; properly trained apron staff (and if there is a low cost airline, the ground handlers as well, as these will generally be skimped by the LCA operator). Did I mention provision of rescue and firefighting services (dictated by the aircraft size)? A regulatory requirement that is costly but inescapable (a major firefighting vehicle with the appropriate amount of extinguishing media, and a host of other specifications, costs about £300,000 - they will need at least two for 737 sizr aircraft ops).
The costs soon mount up, and it is never really viable to try and provide the services on a part time basis. I expect the TDC studies will show that operating Manston as an aiport (with what airline and source of passengers I know not) will be a huge drain on financial resources.
Sorry to sound like a Jeremiah, but that's just the realities of the commercial airport/airline business today.
Mister B