This is definitely an interesting trade scenario, lol.
Firstly, I don't think a new type of trade (or one that wasn't explicitly explained as an option beforehand) should be allowed midseason. It should have been vetoed and tabled as an issue to vote/decide on the following season in 2013 (I also think the fact that the commish was involved in one looks bad even if it was honest). Above all else, a league had to protect it's legitimacy and integrity or it's not worth doing.
That being said, I don't like rent-a-player here. It adds an extra and IMHO unnecessary level of complexity. Now when I trade with someone I have to look at their roster AND their trade history to make sure I'm not make sure I'm not making them too strong. Whether it means to or not, it just has a shady feel to it that can affect the league's perception to the other owners (I'd be totally against it).
I definitely don't like the second scenario either. More than anything else, it just seems like a way to cleverly circumvent the rules. As I said, from a practical standpoint it also adds a level of complexity that the league may find gets too crazy to keep track of.
Curious to see how your league goes on this.