It wasn't much of a loophole, anyone could still have drafted Newcombe. Nominating your contract size seems reasonable to me as it is a huge thing to pack up your life immediately and move to an AFL club for potentially only a few months. Being able to say, "I want a 2 year guarantee to move my life" seems perfectly reasonable.
What the AFL have done is to try and ensure all clubs are able to view and assess potential mid season draft prospects by making sure only those who nominated for the last draft are eligible. That way clubs can't hide players and then snare them in the mid-season draft and it's why we didn't get Strom for Valente (although how are we hiding a 28yo bloke who's played WAFL for years).
However as per the original article I posted, there are exemptions to that with Strom and Derksen now allowed to nominate for the mid-season draft despite not nominating last November. If either of them wanted to nominate contract terms to be taken, they are well within their rights. I would hate to be Strom who is a successful physio, has a life and business outside of football and then is selected for North Melbourne. He moves over, doesn't play a game (the majority of mid-season draftees don't get a game) and then gets delisted at season end in a few months time and has to move everything back. The players deserve a say in their contract.