The "other" category in the RAND report should be considered people who would otherwise be uninsured. To move out of that category, is to move into a prime uninsured pool. It means you've ended your service to the US Military or are a dependent who turned 27 years old. These are life events which happen yearly regardless of the law's existence.
As noted in the graph he posted: 1.5 mil of the "others" moved into no insurance, 1.2 mil others bought on the marketplace. So, it's actually more like 2.6/3.9 not 1.4/3.9, when you consider that the others did not lose their coverage because of the law and would be uninsured today without the law.
But again, it's just another Op/Ed writer twisting in the wind, making bold statements in his headline and then weaseling around things he doesn't understand and hedging his bets with hearsay.
