I agree that there should be an alternative, open-source project, though I know I'm not all that qualified to support outside of financially, (which I would).
I disagree that this isn't taking up space. Notoriety is a huge asset, especially for tools like this that rely on crowd-sourced information. It would be far better, all other things being equal, to start with the user base and name of ICEBlock than to make a competitor and need to promote it enough to get people to use it over ICEBlock. I highly doubt that a competitor will get anywhere close to the same media attention that this got.
It was BlueSky, not Mastodon and is linked in the article: https://bsky.app/profile/grapheneos.org/post/3lt2prfb2vk2r