I suspect that of "continuous presence in low orbit", "longer term new capabilities", "in budget", and "commercially successful" NASA is going to be forced to pick one or two and that's what they're resisting. Rushing things along almost always costs a lot of money and features. If you want to hit a budget and features then you have to be willing to wait for the various bits to line up and preferably spend some time experimenting and exploring new capabilities and strategies before big hardware commitments. There's a lot of moving parts here to think through. This would all be true even if that was NASA's only concern, vs going to the Moon and all the normal and importance science and so on they're getting pushed on.