I think the bootstrapping should be more open-ended, and I'm skeptical of stuff that tries to put things on bitcoin. OTS is a neat idea, but it's centralized in practice, and isn't long-term economical. This seems similar.

That said, it could be one good way to do it, although my ideal would be to use the web of trust to validate bootstrapped-trust providers, who would vouch for new pubkeys (using a badge or something). How the new pubkey gets that badge would be completely open-ended — it could be a captcha, payment, proof of work, KYC check, whatever. The badge would then expire after a short period of time, during which the new user would want to gain followers to get into the web.