Fair call on the gimbaling at the end, in that instance it does impart a moment around the CoM and will invoke a torque, though that's really only at the end on

Fair call on the gimbaling at the end, in that instance it does impart a moment around the CoM and will invoke a torque, though that's really only at the end once much of the vertical velocity is cancelled. As a result it does represent the inverted pendulum right before landing. Interestingly, because the CoM is so low due to the low volume of fuel by the time of landing, it's likely not as big a torque as you'd first expect (all the mass is down the base where the engines are). In that case, rocket height isn't going to have as a big an impact because it's not like it's equally dense up the entire rocket structure. I'd argue he's likely overstating the effect of rocket size on how difficult it is to achieve.