There are also lots of other interesting clients not from Tapbots. If losing Tweetbot was enough to make you look at Mastodon, keep that open mind and look at all the interesting clients out there.
Good news: It looks like that's since been resolved shortly after Gruber's post. https://mastodon.social/@icecubesapp@mastodon.cloud/10971756...
For what it is worth, in my own iOS usage, I used Mammoth for a few months (and still follow its developer) and then eventually settled on Toot! Toot!'s developer was on hiatus just before Mastodon 4 (and the Twitter meltdown) so it got mentioned as "no longer maintained" or ignored/overlooked entirely by a lot of suggestions lists for people coming fresh to Mastodon. But it was rock solid and feature complete with Mastodon 3.x and the developer had earned a hiatus for a job well done. The developer also came back and worked to quickly catch up on Mastodon 4 changes (none of which had been truly a show stopper, mind you), though I think a slight bit late for so many newcomers from Twitter seem to have overlooked Toot!. Anyway, Toot! is great if you need a recommendation from a random HN user who has been Mastodon since a previous era. (I started getting serious about Mastodon round about 2016, myself.)
I'm in the class of iOS users without any personal macOS devices, so that's not a consideration I was aware of, but that does make sense.