There's one reason of import for a fusion system to store hydrogen as LHyd rather than other hydrogen-bearing compounds... mass efficiency. 1 Ton of Hydrogen as LHyd masses 1 ton plus container, and 14.1±0.1kL, exact volume varying by pressure and temperature.
1 Ton of Hydrogen as dihydrogen monoxide (water) masses 9 tons plus container... but loses almost none to container penetration, and takes only 1±0.02 kL, and can be stored at room temperatures.