While changing the spacing of the cabins on the line changes the capacity, you must also consider the weight capacity. You might be able to space them closer, but might not be able to get away with the weight. Unsure how having the system on largely level ground affects things. In general with ski area lifts, they tend only load passengers one direction.
Long story short this application has a few minor differences that could affect capacity compared to traditional ski area install.
While you could have 2 separate haul ropes leaving the Riviera Turn/load station, it would appear seamless to a guest and seem like one line. Not certain they'll do that, but it is certainly possible. If they did that it would allow to operate as separate lines if needed for some reason, which is a redundancy I could see Disney welcoming.