I've only read about it but apparently you can get them out relatively easily if you're hands on and don't back down from any of their schit.
Their strength is their audacity. There are even dedicated "teaching" sites on how to go about claiming other people's schit:
https://reclaimportland.wordpress.com/about/As stated Oregon has a "ten year rule" regarding squatters. If they've been there a long time he's going to have a legit legal battle.
