Its still worth testing. Not all scenarios are managed by bad actors, so if this has positive results in those situations it may lead to the creation of more tools that could help.
That said, I am sure people are currently finding ways to correct themselves. The main thing here is that the original incident itself is modified.
When social media channels are new, the bad faith actors are small and legitimate discussion can occur. As they age, people get burned more often and a higher proportion engages in the contagion.
Currently I am liking the look of this proposal a lot! I've been trying to imagine some scenarios where it could be used or abused in a negative way but so far I haven't come up with any.
Could you go into details on how you're thinking this would play out? I'm not sure how a bad actor would exploit a tweet with a mea culpa flag like this on it. But I am not as imaginative as bad actors.