Most climbing helmets these days IMO are really poorly designed for serious impacts and are rather delicate. Check out the shitty coverage most afford the front and sides of the skull. I think they're designed more to be light and comfortable so that people will wear them. It's a catch-22 since if it's a hard shell 5 pound motocross-style helmet, nobody would wear one.
I'm glad this poor guy had something on his head though and hopefully it reduced the impact and extent of his head trauma.
I think climbing and motorcycle helmets have very similar idea. The hard shell ones actually save the skulls from impact more but end up snapping the neck or result in massive inner head trauma from force. The foam lighter "cheaper feeling" helmets are meant to shatter and absorbs more blunt force.
I think the rule of thumb for helmets is that the hard shells protect against rock fall which is why you'd see more rock guides using them. The plastic foam ones are much better for falls involving head impacts. The worst case scenario is using a helmet that has a plastic outer shell with no foam where you actually hit your head. You don't get the hard shell benefits or the foam absorptions.