Now you, and he, and everyone else here can bandy words all you want about the meaning of the words "criminal" or "illegal" all you want but none of you are really engaging in the most pertinent issue at hand:

But it really isn't "bandying words", exactly. The law is what it is. So called "technicalities" are part of the law. One thing is a crime, another isn't. The law has to be very precise to remove as much prejudice as possible from proceedings that could result in deprivation of freedoms for an individual. If you have your PhD in a hard science, you know that how you phrase something affects the message being relayed (for example, in a paper). Same thing for the law.

What should be done about them?

NOT what we presently are doing. The net is too wide, it's catching people that shouldn't be caught, which results in unnecessary expenditures of resources (e.g. flying a dad and son to TX, only to figure out they can be here, and then fly them back from TX). Not sweeping courthouses for people that are doing what they are supposed to do by showing up for their court dates. That actually has a negative effect in that now they are afraid to show up for their court dates. Nobody who has paperwork pending should be rounded up and deported, at least in part because they aren't "undocumented"...they have documents that allow them to be here until their case is adjudicated. If they don't show up for their case, issue a deportation order (and then deport them when they are found).

The Felon said "worst of the worst" and "really bad dudes". OK, I can get behind that. The bad ones, send them to prison for whatever they did, and then deport them when they served their time. Have ICE waiting for them at the prison gates. I don't think you'll get much argument from anyone about that.

I think the entire system needs reforming (even before Noem and Miller started the pogrom). Lots of moving parts. With that caveat, what to do with them? If they aren't bothering anyone, then just deal with them if you catch them doing something. For example, while being undocumented in this country is not itself a crime, having phony documents is (e.g. a phony SS number...I looked that one up just to be certain). If they do the latter, and you catch them, then deport them. If they're living quiet lives, leave them alone. They'll never be citizens, and if they tried their status would quickly be determined, and they'd get deported. If they run afoul of the law, deport them (after whatever appropriate punishment for whatever offense put them afoul of the law).

If we put the onus on employers to determine resident/work status, most of the undocumented population would self-deport because they couldn't get a job. No job, no ability to stay here. That would likely solve 90%+ of the problem right there. That remaining few percent, as long as they aren't doing something bad, ignore them. Not worth the resources, and lives lost, to hunt them.