It's not just that idea though. Plenty of presidents have done that without pushback. It's that idea combined with:
* Rhetoric dehumanizing the immigrants
* Raiding churches, courts, jobs, etc
* Revoking legal status of immigrants
* Reducing training time for new hires
* Detaining U.S. citizens and threatening them
* Saying it'll help the U.S. citizens, when data shows it doesn't
(2) -- why can't you raid a church? A church is not a special place. America is not a theocracy which gives sacrosanct respect to some portions of land.
(3) The US has every right to revoke legal status with no other reason than it doesn't make sense for the United States. We can talk about how it's done, but that's rarely the issue at hand in these debates.
(4) Not sure what this means
(6) Politicians say incorrect things all the time to appeal to their base.
I know one of the lead protest organizers where I live. They have a long list of things. Things they feel are bad and want reversed. And having known them for a long time, I can say they are internally consistent, and would be out there protesting if it was a Democratic president doing this, or more likeable person doing this. It's less about the hate, and more about concern for the direction things are going, and blatant disregard for the law.