I don't think that's true at all, most people I've come across use it in an off-handed way to express solidarity with victims of police violence, or their general distaste for racialised and/or militarised policing. Full-fledged abolitionism is rare.
They really say it because they hung around in left-wing spaces for a few months in 2016, and it's vaguely anti-authoritarian. It's the same place they got "tankie" from, although they think it has something to do with Tienanmen Square.
