The problem with diesel is that there has been a cap in their efficiency for quite some time. We've pretty much tweaked as much speed and efficiency out of what is possible with diesel tanks, which is why the Abrams has a turbine engine.
As tanks become heavier and heavier the only real solution is to migrate to electric motors, which are more efficient and vastly more reliable than diesel or turbine.
Just like with trains, the future of tanks are electric motors, and until we find a battery material more efficient and safe than lithium, hydrogen fuel cells are likely going to be the solution.
My point is that if your tank's armour is compromised by modern antitank weapons, it doesn't really matter where it hits you. You're going to be turned into chunky marinara, or your shells are going to cook off.
A pressurized fuel cell is already more protected than any fuel tank, and is smaller and lighter and more efficient than any ice engine. Which means you can add and divert even more armour to protect the cell and the occupants of the tank. Basically any danger associated with hydrogen is vastly overshadowed by the fact that tanks already carry high explosives. And that's not so dangerous that we're trying to replace them with non combustible weapon systems.
It's not like Rotem is new at making tanks, the K2 is one of the best tanks currently in production. If the engineers thought fuel cells increased the likelihood of catastrophic failure, I highly doubt they would have tried it with the K3.
Personally, I think most people are just buying into the propaganda that shut down hydrogen power in the first place. To my knowledge there hasn't ever been a death associated because of an explosion or fire involving a vehicle with h2.