Twitter is clearly drawing a line somewhere about what violence is okay, and what violence isn't, and it's not particularly clear where it is and if there is any bias.
It is worth noting that “state-sanctioned” violence does not always mean legally-sanctioned violence, since state actions can easily be criminal, or at least lawless.
- The Capitol Hill mob was illegal violence, albeit state-sanctioned (by endorsement of the president)
- Arresting the president (either under Congressional authority or the 25th amendment) would be legal state-sanctioned violence
- Although nominal Chinese law is somewhat authoritarian with regard to ethnic minorities and Muslims, the reason the Xi regime is so desperate to cover up and propagandize the concentration camps is that they are illegal under Chinese and international law
- an illegal mob ransacking Congress in an attempt to overthrow an election, and
- a constitutional arrest of a criminal president (e.g. by the House Sergeant-at-Arms, or by the FBI under Mike Pence’s and the Cabinet’s order via the 25th Amendment)
should not need an explanation.