What he's being 'slightly misleading' about is that while a puddle of diesel IS indeed hard to ignite, a finely atomised mist of diesel is far from hard to do so (indeed I have had a fire myself while working on a diesel ute with a faulty injector (brand new, just fitted) which caught fire when spraying finely atomised fuel)- all it takes is a pinhole leak in a fuel rail or line and an ignition source...
(one of the main ingredients in modern napalm is... diesel!!!)
Sadly the conspiracy nuts and the anti EV'ers have joined forces and have been pushing this nonsense widely (this is the second forum I have seen this garbage popping up in the last couple of days)