Twitter, though, at least has moderators, and makes an effort to remove threatening content from its service. The speed and efficacy of Twitter's abuse team is a topic for debate, but they have (and enforce) policy.

Parler famously had no such policy, that's why it was so attractive to the insurrectionists. The CEO, even after January 6th, went on record that he didn't feel it was Parler's responsibility to moderate user-generated content at all. Whatever last-minute olive branch they tried extending to AWS regarding a potential future volunteer moderator system obviously wasn't sufficient for Amazon.

Twitter and Facebook took how many years and millions of dollars to scale up a moderation strategy? I guarantee they weren't worrying about moderation at Parler's scale.

Twitter didn't take him down for a week, but they took that post down faster (I think). I regularly report twitter posts that are similar to that - violence mostly. It often takes two or three days, but they do get them taken down.

Too busy to moderate Trump's inner circle.