I think they kind of have a point; they were talking about needing a 10kW transmitter - that's a heck of a lot of power for a transmitter, not easy to make at all. And at those frequencies, the antenna is a challenge.
Having said that, a bunch of few-hundred W transmitters in convenient places would be a lot easier, and there are probably easy but inefficient antenna hacks (drop a wire down a cliff/across a park/out of the top floor of a tower block?)
I beg to disagree, 10kW at ~140khz is actually relatively straight forward with modern semiconductors and LiPo's. Eg. the inverters in a Tesla Plaid can do up-to 750kW, so I think two orders of magnitude more power is theoretically possible.
And then they left out that at such long wavelengths there are some unconventional antenna topologies available. Some of which are a lot more feasible than anything that was discussed in the talk.
