That's his point, the resource is available, but the answer as to how and where is not actually available. The whole point that I got from the paper is to get people to work on better processes for extraction in order to be able to feed the battery need, because the current supply will not do it. It doesn't answer how, it just notes that the resource is abundant. To reiterate, where all the strip mining will happen is not answered, because the processes are not in place to decide where it will be most profitable to do it.
Interesting as well is that the only environmental impact that they mention is carbon dioxide emissions, which for one was 5 tons per ton mined, and the other has no stat but is estimated to be twice that. Doesn't sound very carbon friendly but I suppose since I don't know enough about the context of those numbers I could be wrong on that. And that doesn't take into account how much CO2 it takes to actually charge these batteries, another thing that the green energy folks continue to ignore. No mention as to what environmental impact removing tons of lithium from the oceans or the brines actually means to those environments either. I suppose the idea is that it means zero, but I'm guessing we thought the same about burning fossil fuels way back in the day with CO2 emissions as well.