There are some strong assumptions behind this article, it chooses the following scenario: Wind + Solar + H2 for seasonal storage. And then proceeds to dismantle it. But nobody said this has to be the scenario.

I think it's far more likely something like: Wind + Solar + hopefully clean base load (e.g. Nuclear) + Hydro + Hydro storage + Lithium storage + H2 storage for transport (planes, trains, ships) + H2 storage for seasonal purposes

Fact of the matter is, there is no clean alternative to H2 (at the moment) for large transport vehicles (i.e. cargo shipping, planes, trucks) so unless you are willing to keep using carbon based fuels for these purposes you are stuck with H2.