I disagree with that a little.
Rondo likes the ball in his hands, and without it he is a burden because of his shooting.
Since Cousins is so dominant and likes the ball too (and to a lesser extent Rudy), it can be a somewhat awkard fit, since as a team I think we are better off with the ball in DMC's hands. On the second unit Rondo (in theory) can make a limited offensive five with some shooters and slashers that doesn't need the ball to be effective into an effective bunch.
While he doesn't qualify as the traditional "spark plug" PG kind of guy, I think that there are benefits with playing him with the second unit, and I honestly think the starting unit is better with DC (the +/- of that core was very good last year).
My worry in that regard is how Rondo is going to react to that, especially considering it's a contract year for him and being a back up can potentially cost him money.
Cousins' "ball dominance" is being dramatically overstated here.
Yes, Cousins might be the GOAT ballhandling center, and he handles it much more than other centers. But he's still a center. We have stats for this stuff now, and last year Cousins had the ball in his hands a grand total of 2.7 minutes every game. 0.1min a game longer than Blake Griffin's 2.6. Rudy Gay had it a further 2.8min, which is the same amount of time that Kevin Durant had the ball.
I'm pretty sure that Rondo will survive without the ball for 5.5 of each game. Last year he had the ball himself 6.5min/gm. Which was likely artificially low due to Dallas wanting him to share control with Ellis. Collison actually had it 6.9min/gm. The league leader was (and is normally) Wall at 8.2 min/gm. But that number is fine because Wall uses those minutes to set up teammates as does Rondo.
If CP3 (7.8min) and Blake (2.6min) work ok and Westbrook (7.7min) and Durant (2.8min) work ok, Rondo and Cousins or Gay should be fine, and even Cousins and Gay together can only be a minor strain, because Ben McLemore can't dribble and barely touches the ball, and a Kosta Koufos or WCS is going to be the same. Defensive roleplayers, almost a forgotten concept in Kings land, can always free up your stars/ball dominant players to be themselves. I think in total we're oversubscribed, time of possessionwise, by maybe a minute. Not 100% perfect, but surely workable.
For a great 1 on 1 player, a PG is kind of a luxury anyway. Rajon Rondo isn't really there for Cousins or even Gay, although he can help him be a tad more efficient. Rondo is there for the rest of the guys. I'm more worried about Karl's "ball don't stick" offense than anythign else, since almsot by definition the ball sticks to great PGs. Steve Nash was a hugely ball dominant player too. If George Karl kept on screaming at him to give the ball up every 2 seconds he'd be an idiot. You accept ball stickiness from great pure PGs because its sticking to them for a team purpose. They aren't probing looking for themselves, they are looking to set up somebody else, which is the whole point of ball movement in the first place. With a great pure PG the ball movement is just being accomplished with a PG attached to the ball.