They’re assuming a monopoly on load-shifting the cheap power.

Any process with fixed costs lower than the electrolyser will just expand that stage of the supply chain and buffer the inputs and outputs.

Industrial heat is trivially stored at much higher density per volume in bricks, sand, or graphite.

Low grade heat is way easier to store in a pond.

Any variance with more than 100 cycles/yr is better served by batteries.

So you’re left with electrolysers running at 1-5% capacity factor if you want the “unwanted” electricity. Otherwise you’re paying the same as anyone else not drawing from a battery.