In my personal experience, most of the ACAB crowd I know are pro 2a. Granted, most of the ACAB crowd I know are very far left, and believe that arming minorities is important to prevent them from being pushed around by the state. They also support abolishing the police, and a minor part of that mindset is focused around self defense.
I think the divide falls moreso within the Abolish the Police vs (De)fund/reform the Police crowd.