The difference between the possible strikes and the guaranteed Champions League final is just that. The strikes may happen. Around 12 months of planning went into the Champions League Final when at Manchester. Best case Manchester has had 3 weeks notice of iminent strikes. On CL day runway 2 was used as a extended ramp with countless exec jets and MD's parked over there. There is simply no time to set this up in time logistically.
I believe however tech problem is partly correct. It is not a case of no slots being available any more it is just the fact all slot applications are being handled manually for these particular dates.
If the strikes go ahead, the traditional handlers of Ad-Hoc flights, Ocean Sky and Flight Support are no doubt going to be busy as well as Servisair in particular who have a hell of alot of 'diversion' contracts on their books. Lets just hope BAA sort out this mess and the 7th, 14th, 17th & 18th are just normal days at the office.