Well, there’s this by me:

> Do you know how many of the people arrested in connection with the Capitol invasion were active users of Parler?

No, and neither does Greenwald, because its not like Parler has a real-name-to-account lookup function he has access to, or authorities have compiled and released breakdowns of all the social media accounts of arrestees, etc.

At best, Greenwald is fallaciously treating absence of information about their Parler use as information of absence of such use, at worst he's just making stuff up.

> The planning was largely done on Facebook.

Planning, including for the violence, was done on Parler among a wide variety of different sites. Actual journalists who are interested in investigating and reporting facts, and who haven’t abandoned actual journalism for pure ideological propaganda like Greenwald, have covered this, including the content of specific posts:

https://theconversation.com/far-right-activists-on-social-me...

https://www.propublica.org/article/capitol-rioters-planned-f...

https://www.forbes.com/sites/jemimamcevoy/2021/01/07/capitol...

https://www.vox.com/recode/22221285/trump-online-capitol-rio...

Where did he get his data from to assert that with confidence? Also, how many people had been arrested in total at the time of Glenn's tweet - I have a feeling the number is going to go way up, and with Parler data becoming public, it will be easy to disprove his assertion (which may be technically true, but has low information density)