But declining to QO doesn't open up cap room. The Bird rights still have a cap hold.
I don't see any cap "loopholes" here, and I think the CBA was designed to specifically avoid them in this area.
The only thing that really makes sense to me is that the Kings - for whatever reason - didn't want to risk having DDV on the payroll at $6.6M for one year (that's the risk of him accepting the QO - if he got an RFA offer we didn't want to match, we could just decline to match). So do they think that's an overpay? I kind of doubt it. Which means they're either happy to move on (also makes little sense given the pursuit) or they've got some irons in the fire that, if they come to fruition, would make them regret a DDV contract at 1/$6.6M. Or maybe Ham was right and DDV was super unhappy and so they just let him go rather than try to coerce an unhappy player to stay.
The last one almost makes the most sense. RFA allows the Kings to let sit back and let the market dictate the contract. DDV may have felt that the Kings used him in such a way as to depress the value of that contract, and if he's going to come back, it will be on his terms (years/$$) in an open negotiation rather than in terms of what a depressed market might offer. And we figured we'd rather not have an angry player, I guess?