The only positive I can think that FCH has over BEV is filling time, and even this will become more irrelevant over time as charging speeds increase.
What's more, H2 filling times aren't what they are cracked up to be. While fueling time is often quoted as 5-10 minutes, the reality is that's an ideal that won't be typical for a moderately busy station. Current stations used by cars for H2 have cycle time issues where the pressurization and cryo steps necessary can make the process far longer. (See the owner above who talks about this along with frequent outages).
I'd assume that the larger capacities of H2 needed by semi's would exacerbate this problem. There's every potential that this means either:
1) The time advantage as compared to Megacharging doesn't really exist in practice
or
2) The fueling infrastructure for cars would be inadequate for semis and in effect the infrastructure here is effectively non-existant still. (Logisitics may compound this.. are the H2 stations used by cars large enough to even practical to route a bunch of semis with trailers through ?)