> I would think that a big problem here is to only allow correcting typos, not changing meaning of a tweet - which would suck for a public, fast-paced platform like twitter.

I feel like GitHub already solved that problem by showing an edit history on comments. Twitter could do the same thing.

Even easier: don't actually publish tweets for 60 seconds, during which time they can be edited.

Instead of rendering it as hidden or even as an edit history, render it with an "inline diff" (using the kind of algorithm you see Wikipedia do, or GitHub within a line) as a cross-out of the old content and the next content next to it... changing a lot of text like that would be extremely noisy and obvious--to the point where it wouldn't accomplish any evil goal and would also just be generally discouraged by its nature--and yet would fully solve the vast majority of cases that we want to satisfy.