He said it was about free speech but Twitter is already about as free as it's possible to be without permitting a whole bunch of content that is NOT protected under the first amendment (CP, calls to violence etc).
And if it is about free speech then it cannot be an automated moderation play, because there is nothing to moderate if you're a pure free speech platform.
The best I can guess, is it's a political play? Turn down politicians who he dislikes? Or he just had a drunk/high/bipolar period and did it without a plan.