This is largely FUD. Previous industrial H2 use made H2 as a Natural Gas or Methane derivative.

Hydrogen production from electrolysis is being expanded. Hydrogen is favored over other fuels because while it can cause enbrittlement, that can be accounted for by using materials resistant to that. It's how we've handled hydrogen for decades till now, just not in the retail sector, but also why it would not be pipelines around the country like Natural Gas is with the same pipes. This is a solved problem.

Hydrogen when used in a fuel cell or in a hydrogen combustion engine produces 0 or near 0 emissions. That is one of the biggest appeals here. The emissions of a hydrogen fuel cell is water, H2O. You can drink from the tail pipe (don't). In HICE engines, the emissions are a microscopic amount of NOx fumes, in a different world from existing gas or diesel engines.

This positions hydrogen as a much more scalable and less polluting fuel than even batteries long term. And much, MUCH lighter than batteries of similar power density. These are the appeals.

Also, while volatile as a molecule, it's also quick burning and the smallest molecule on the periodic table. Meaning a 700psi tank that has a 2in tear in it, would entirely vent /burn in around 30seconds to 1 minute. Because the molecule can literally leave faster. Unlike the never ending fires that EVs have when they light up, a H2 fire is over rapidly. There are also safety measures like quick disconnects involved. Finally, the tanks are carbon fiber wrapped and reinforced, and the tank of the Toyota Mirai can resist fire from a AR-15 directly. Puncturing these is hard.