I see. a brief google search didn't bring up anything in relation to the leading zero concept, but that helps. at a brief glance, their use of the leading zero seems like ... clever marketing?
my analysis of it is that it's a way of making people wonder "oh why is he writing it like that?" like I did, lead them to the foundation, and have them engage with it and be aware of it in the future; i.e. marketing. it's quite clearly not a practical thing. the probability that by the time 10000AD rolls around we're still using the same year system, we're still alive as a species, we're still technologically capable as a species, and we don't have the capacity to understand older years minus the leading zero seems near enough zero to be zero. call it what you like, marketing, inspiration, whatever, but it's a sneaky way of leading people's thoughts onto a particular pathway, which I call marketing
to be clear, having read through their website, I think what they're doing is great, and this isn't a criticism
I was born in the 20th century. I was filling out a medical form and put my birth year in with 2 digits. The web app took that to mean just the 2 digits. No, I wasn't born in AD 70.
That's the kind of programming that makes you reluctant to put anything into it.
Not using leading zeros seems fine if you're using AD near it to indicate that it's not 1942.