Earlier quoted context omitted.
People seem determined to write things on Twitter that are absolutely begging to be taken out of context. Sarcasm, inside-jokes, rhetorical hyperbole, assumptions that everyone is following the same story they are, and so on. I don't know why they do it.
The simple answer to this problem has been clear for awhile: Make responses to quote tweets opaque to the original author. 1. Bob quotes a tweet from Alice he thinks his followers will find enraging 2. Bob's followers reply to the tweet with predictable outrage and abuse 3. (present system) Twitter becomes unusable for Alice as she is flooded with mentions from all of the angry and abusive replies to Bob's quote 3. (…
> 3. (proposed system) Alice is not shown any of the replies to Bob's tweet. Bob's followers scream into the void.
The problem of online harassment is not (mainly) that the service UI becomes cumbersome to use for the victim. It's that everyone else can observe they are harassed and the victim loses control over their online presence. Your proposal would actually make this effect worse, because the victim wouldn't even notice anymore they are harassed.