Of course, common sense to yehi kehta hai, however what's there to hide about MoD since iSi is mentioned no where? Also, at what stage the successful candidates come to know the fact that they are part of iSi? Either it is when they receive their final appointment letter or when they reach to the place they are told to, an academy or whatever?
I seriously suspect that things aren't that simple as they appear to be and the whole procedure might actually be just to pretend that iSi is recruiting its mainstream personnel while the real thing is happening some where else. They don't bother about applicant's feelings and their exercise in vain is evident from the fact that they don't care notifying the candidates not qualifying a certain stage.