The lady in question has no active account at present.

The old account may even have been deleted.

The old email address is no longer active - so to sign up with a new email address will not be a problem.

If, as Etihad reserves the right to do in sections 4.3 and 4.4 of the T&Cs, the "old" and "new" accounts are merged, then the outcome would be no different from what I have advised the OP to do.

Unless Etihad decides to merge the active account into the inactive one...

How about we compromise and say that the OP's wife should exercise her right under 2.4.1 of the T&Cs, and notify Etihad in writing of her wish to terminate her membership of the programme?