I sympathize, but I have little patience for calling out your data provider when disaster strikes. Sure, there is likely some technical fault on their end, but ultimately you are accountable for your own site. I'm not going to imply anything negative about him for losing the site temporarily. We all have "learning experiences"... I just hope that when he does come back, he posts an insightful analysis of how he could…
That's not too far from saying that it's your fault if you get hit by a car while walking across a crosswalk because you didn't jump out of the way fast enough.
They failed, they failed in a catastrophic way, and they deserve to have it made public knowledge and to lose business over it. He should do a better job backing up his own stuff, but he's right to be angry with his hosting provider and to call them out.