I think its an insinuation that letsencrypt is a honeypot.

It's been long rumored that privacy-as-a-product companies are actually three letter agency honey pots. ProtonMail actually has some connections to NSA investment firms and some former NSA staff on their board. There could be good explanations here, and there could be bad explanations, however, we don't know the role each of these components play in the larger sum; we can only guess and speculate.

In that way, an ambitious project that gives away certificates that were formerly worth a lot of money would be a pretty slick honeypot because now you could stow away private keys and have a copy of most of the encrypted webs certificates to decrypt in-flight communications.