Of course it's a crime. The obvious ones are:
Lying / with-holding info from the dvla (punishable by fine & possible prosecution as per their website)
Lying / with-holding info from the police who came to the scene and investigated (ie he didn't say "oh I blacked out well yes this has happened before did he) so that's got to be a crime
I cannot for a moment understand why this (driving when impaired) could not be prosecuted under reckless endangerment / dangerous driving / some other thing. Laws are written quite broadly so as to give scope when a prosecution is desirable.
Bottom line is the dvla could have gone after him, and I'm sure if the prosecutors had been interested they would have found something to get him under. Because he lied to the dvla (by omission), he lied to his employer, he lied to the police, he drove when he knew he was impaired, he had blacked out at the wheel before leading to a loss of his job, and he killed 6 people.
Then after he killed 6 people he asked for his licence back a handful of months later, which is obviously not a crime, but certainly speaks to his character and demonstrates that he a. couldn't give a fuck about all those people he killed (15 were injured as well) and b. is quite happy to take the risk of it happening again.
"These things do happen and plenty of people prone to fainting or worse drive. I do not think the focus should be on the driver"
Bollocks.
A person unexpectedly falling ill behind the wheel is entirely different to what happened here, and I have literally no idea why some people are so keen to say it wasn't his fault and he should face no consequences.