I don’t have inside knowledge of Twitter’s architecture, and so can’t really comment on whether a “few lines of code” is accurate, but the essence is this: When someone blocks you for whatever reason, you can’t @mention them in a Tweet. Whether you get an error, or it’s just silently deleted, the Tweet will go nowhere and won’t be seen by your followers.
That fixes the biggest single aspect of Twitter’s harassment problem, when someone with a large bully pulpit sets their followers on someone who’s incurred their wrath.
Unless there’s a flaw in the solution I haven’t see, it’s hard to see why Twitter doesn’t just go ahead in implement something along these lines. You’re forced to suspect that Jack Dorsey is less interested in solving Twitter’s actual problems than he is currying favour with particular activist cliques. In other words, virtual signalling trumps positive action.
The problem with Jester’s Court’s solution is it’s politically neutral. The same mechanism that would stop racist and sexist trolls would also damp down the witch hunts popular in social-justice circles. And because that would cramp the style of the people Jack Dorsey wants to curry favour with, it’s a non-starter; they have a weird “punching up/punching down” dynamic where it’s only defined as harassment if it’s a member of their outgroup targetting a member of their ingroup.
So instead Twitter seem to be going down the route of top-down content politicng and filtering by keywords known to be popular with outgroups. What could possibly go wrong?