A small percentage of a large number is still a sizable number.

Flying on 9/11/2001 was "mostly safe" because less than 96% of flights were hijacked. Also a true statement, but ridiculous.

The BLM riots resulted in 19 dead, and thousands of properties damaged. It's equivalently true to say "Trump protests/rallies are mostly non-violent", since the majority of them (probably rivalling the 96% in the article you mention) have had few issues with violence until the recent insurrection. But that would just be a vacuous talking point.