In case anyone is wondering, it’s because it’s a more complex process that removes a lot of the impurities that degrade plant fibers like acids. The fibers are also significantly longer, get damaged less during the process compared to machine made, and don’t have lignin which tends to degrade the fibers in wood based paper.

That 1000 year number depends on controlled environmental conditions or getting left in a desert. You leave some washi paper in a rainforest and it won’t last much longer than other plant fibers.

Could it be his his degree in journalism and his years of experience as a journalist?

I hope positively surprised :) That's Paul Carter - he's a regular presenter on the BBC, particularly their tech show "BBC Click". Here's a nice interview (https://disabilityhorizons.com/2019/09/paul-carter-journalis...) he gave to Disability Horizons a few years ago about his experiences.

I don't think this is just due to lack of good paper making techniques, it's also an aspect of physical security that's involved.