I was thinking that might be what he meant, but then he says this: >While a three-stage rocket is simple and is limited on how much of a weight threshold it ca

I was thinking that might be what he meant, but then he says this: >While a three-stage rocket is simple and is limited on how much of a weight threshold it can lift, the more advanced two-stage can be expanded for larger weights. The first part of that is, I'm pretty sure, the opposite of true. The second part is sort of true, but the "expansion" in question would be... adding a third stage. I think he heard the Geoffrey Forden quote and misunderstood the point, which is admittedly subtle. I think what Forden meant was: "If they need three stages to do just this, then they'll never be able to use this to launch a human, because a four-stage rocket is completely beyond them. But if they can do this with only two stages, they could get a human to space with three stages."