Whilst the situation with Jet is still fluid I suspect if there is any doubt about the service MAN would prefer the situation to normalise first rather than have a chaotic stop/start service and one that is all to evident at Birmingham.
In other words if they cannot commit to a cohesive service , possibly best to wait until they can.
My timeline is STILL showing numerous references to Birmingham a week after Primera have finally canned them.
Its a steady drip , drip of bad publicity.
Much better not to start at all than have an adhoc on-going weeping wound of puss which immerses the airport in torrid publicity on a weekly basis. (see also STN)