And what is not easily explained? We've shown conclusively that NDEs don't require anything at all supernatural.
Perhaps, perhaps not.
If they did a study that showed the people from that group were less likely to try again than other people who had once attempted suicide and were NOT shown the NDE accounts, then perhaps you'd have a point.
But since there was no control group, you can't assume that those people never tried again due to reading those accounts. It could be that the vast majority of people who attempt suicide never try again, and showing them the NDE accounts didn't influence them in any way.
Oh wow, where to start with that...
Dr Stan Grof thinks the tunnel is a memory of being born, which is nonsense because babies being born aren't generally capable of forming memories, and even if they were, they wouldn't see it like that.
It also says that Grof thinks consciousness is "non-localised", a claim for which no supporting evidence is given. And Grof is pretty closely tied to pseudoscience anyway.
And as for the author of that site, Kevin Williams, he's got absolutely ZERO education in biology or psychology or psychiatry. He's a computer scientist. So his articles about NDEs are pretty much worthless.
If you want to read an article about NDEs that ISN'T worthless,
try this one. It's written by Steven Novella, who's an actual clinical neurologist. So he is very well versed on how the brain works - it's his field of expertise and he's been working in that field for more than twenty years.