Earlier quoted context omitted.
Parler has terms of service that prohibit calls for violence. My guess is that the moderators (I'm one) simply can't keep up with the volume.
If you run a social network and can’t keep up with moderation for calls for violence you shouldn’t be allowed to be in business. This goes for the big tech companies as well. “It’s hard” is not an excuse.
Hundreds of hours of video is uploaded to Youtube every minute, you can't have people to watch it through all. Twitter has thousands of tweets a second.
It's impossible to manually moderate social media platforms by your standard, it's the whole point of Section 230.
You remove disallowed content when it's discovered. Parler deletes illegal parleys when are notified, they deleted parleys from Lin Wood a few days ago.