Basically two things: the misinformation telling them that it’s legal (hell, we don’t even expect cops to understand the law in the US, what chance does some the average idiot have?), and the fact that literal law enforcement agents are carrying out these arrests.

All these judges issuing injunctions against the admin’s illegal actions might not be able to take down the melted cheeto directly, but we really need them to go after the people at the agencies going against their orders. The plane that was ordered to turn around? Why wasn’t everyone on that thing arrested as soon as they returned, pilot included?

Can we get police to arrest ice? I think it’s time to find out. Start giving them a reason to think before “just following orders”.

He’s referencing moral frameworks, hence the kohlberg scale comment. Some folks take the law as gospel: i.e., if something is against the law and you are arrested for it, then the only problem is you, the person arrested. According to that mind state, all of the folks who are in america illegally are therefore deserving of whatever the law (sort of says and) does to them.