"thus, you'll depressurise earlier than planned." was the mistake. It was just terminology, I'm sure - you meant, I think, "you will reach zero diff earlier than planned". You will in fact be 'repressurising' the cabin which needs to go from 7000' to sea level.
Yes, I agree; however, as rudderrudderrat mentions, the cabin will now descend at the same rate as the aeroplane. Or to be exact, slightly less, and that you'll have some slight negative diff pressure... near as dammit depressurised; with the exception of course that it's the outside air that's attemting to repressurise the cabin! Semantics dear chap.
I feel sure that if we were within the same room having this very same conversation that we'd all agree.