BTW - just looking at the photos and description of the solo canoe used for that trip (no specs listed that I see), it seems like a canoe that might work relatively well as a poler - for someone with a developed sense of balance.
Also, BTW - the problem I would expect with using a short pole in each hand from seated or kneeling, is a lack of leverage - but not for what immediately comes to mind. If it were just a matter of pushing upstream, one can push as hard or soft as one wants or can tolerate. Forward progress can be made at whatever speed can be managed. But even that blogger mentioned problems with controlling his bow. Bow control requires some leverage - not just with the pole, but also on the pole. That requires two hands. Leverage also may be applied to the boat - not just for heeling to accommodate turns (roll), but also some directional twist (yaw). The best leverage is, of course, standing with both hands on a long pole. Kneeling is a compromise that can work in a narrow solo canoe. I don't see how one can possibly have usable leverage for good bow control with one hand on the pole, even with one on each side.
I think the "two ski pole" method might be useful in some cases - but extremely limiting.