Jack is not a cofounder. Nostr.com is owned by a random user (not sure who, but can probably figure it out). Nostr was created on 2020 by an anon developer named fiatjaf. Jack made grants to nostr devs in 2022 (among other FOSS projects) after he first discovered it. He has no part in the development of the protocol other than the grants, although he is an active user.
Someone's got professionals pumping it, for sure. Along with the recent context-free appearances on the front page, note that this is the 2nd post from submitter @throwaway689236.