Technically I guess I can't prove it wouldn't work if you make it dense/hot/covered-in-reflectors enough, but I'm pretty sure it's _well_ beyond the limits of what a fungus could even conceivably do.
Note that the only numbers on that page have various critical masses in kg. That's a bigass fungus.
And that's still not getting into: the "fuel" here is real shit. It's gotta be beyond its useful life even if you ignore that the thing melted down and corroded and blew up.
Do they? Why not?