The block feature is not there out of the goodness of their CEO's heart.
It is there to limit liability from harassment. After all, why police harassment laws at your expense. When you can get the end user to enforce it for you.
1.2 User-Generated Content
Apps with user-generated content present particular challenges, ranging from intellectual property infringement to anonymous bullying. To prevent abuse, apps with user-generated content or social networking services must include:
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The ability to block abusive users from the service
User Generated Content
User-generated content (UGC) is content that users contribute to an app, and which is visible to or accessible by at least a subset of the app's users.
Apps that contain or feature UGC, including apps which are specialized browsers or clients to direct users to a UGC platform, must implement robust, effective, and ongoing UGC moderation that:
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Provides an in-app system for blocking UGC and users;
Every day he further proves that he has no idea what he's doing. He's 100% going to reverse this decision when he find out all of the things he should have know before saying anything.
I can see him choosing to leave the app stores like epic did just to dodge the 30% cut. And of course he will put on a bunch of theatre about "free speech" if they do unlist Twitter.