Typically coal contains between 0.2% to 5% sulphur by dry weight. British coal is quite low in Sulphur, which is why is was criminal to allow coal mines to flood and instead import high Sulphur coal.
Anyway, it is a low amount, the only reason it is a source would be because we use so much fossil fuel and have nothing else to do with it. I can't see it really being a "resource crisis" as claimed because you only need to go to areas with volcanic activity to see almost pure Sulphur deposited around the hot springs and pools. Such volcanic deposits are already mined for Sulphur in Indonesia, Chile, and Japan. Or you could pipe away the Hydrogen Sulphide gas being emitted. Parys Mountain on Anglesey has lakes of concentrated Copper Sulphate in solution that are currently just polluting the Irish Sea.
Sulphur is a very common element on the surface of the Earth, but mostly it is locked away in Quartz, and other silicates, clay minerals, and other minerals, in rocks and as sand. I think that more likely it is "change" that is the worry. No one likes "change".
I'm much more interested in how they are going to make Steel without Coke or Charcoal. Traditionally, Steel is made from heating Iron and Carbon. The Coke or Charcoal aren't just the fuel, but a vital chemical ingredient in the process. The Carbon is necessary to produce Carbon Monoxide to reduce the Iron Ore (Iron Oxides) and 'steel' away the Oxygen. However, there is some new Swedish process that uses electricity as a fuel and uses Hydrogen as a reducing agent instead. It is called
H2 Green Steel and has a 95% reduction in Carbon Dioxide emissions compared to traditional steelmaking.
Where there is going to be a problem is with some of the extremely rare metals that are required for our current battery technology. All these "green" sources of power generally involve the storage of electricity inside things made only from digging gigantic new holes deep into the ground.
Edit: I should have read the article first as it said some of what I just did. I still don't think the supply Sulphur will be as much of a "crisis" as the supply of Cobalt, Nickel and Neodymium themselves will be. I also wrote a dissertation of the removal of Phosphorus from sewage sludge. Removing Phosphorus from freshwater supplies isn't that easy, it's just easier than removing the sources of Nitrogen if you want to stop algal blooms. I also wrote a dissertation on Sulphurous Mine Drainage, which is even more difficult to remove, but right there you have another source of Sulphur.