At the risk of being lynched I don't think he should have been jailed and I think the judge got it about right. As heart-tearing as the story is and as hideous as the consequences were.
It looks to me like there was no evidence of willful neglegence or mallace of forethought. I'm not saying there wasn't either of those two things present. Just quite likely not enough evidence to suggest either. And evidence is obviously, and rightly, ALL they should go on. Not photos of burnt people or stories of heart-wrenching heroism. The effects of your crime are only relevant if you are demonstrably aware that they might occur. Otherwise, no matter how hideous they might be, I'm afraid they're just not very relevant. It's why we don't jail children. Or, rather, why we shouldn't.
He very liekly didn't leave that place thinking "I better hurry up or they'll blow up if someone sparks a cig." It was technically an accident. One down to unbelievable, inutterably huge levels of stupidity and ignorance, yes. But that also almost vindicates his defence. Who but someone who had not the first idea about what he was doing would have done what he did? I'd take some persuading he had the slightest idea it was even a risk. Or at least what consequences might be involved. He was probably just an imbecile, a low-level fraudster and someone who egotistically thought he knew a lot more than he did about the things he did. So what punishment should that type of person get when - as statistics would have it - one of them is the cause of a disaster...
When we see something that outrages our senses, pulls our heartstrings and rightly inflames every moral sensibility we can forget that the only things that matter when trying someone is what you can prove. You'd want the same if it were you. This must mean the odd shockingly dangerous, unthinking, cheating, stealing excuse for a human being gets away with near murder. Currently, that's the best system we've come up with. The judge had a hard call. I think it's too easy to presume they're soft or idiots. I think, given the system he HAS to work within - he judged correctly.
p.s. trust the daily mail to mention the price of the house...