There are two reasons Tucker Carlson treats a "guest" on his "show" this way.

1. It's illegal for him to commit physical assault on another person, his legal department says.

2. His audience wants violence against people of Mexican descent. They'd watch "Punch a Mexican with Tucker Carlson," and Tucker would host such a show for money, but Standards and Practices might have a problem with it.

I literally have nothing nice to say about Tucker Carlson, at all, ever. He's a terrible person and he's paid by Fox News to do this. (Transcript from Media Matters)

TUCKER CARLSON (HOST): As an American let me explain our system to you I know that you're here illegally.

[...]

CESAR VARGAS: As a nation, we have matured from only free, land-owner white people --

CARLSON: Don't hit me with the race crap, okay?

[CROSSTALK]

As a citizen of a country controlled by the conquistadors don't lecture me about that stuff.

[...]

CARLSON: I don't know what chutzpah is in Spanish, but for you sitting here illegally and we're not reporting you or having you like, tasken out by force.

VARGAS: And you know what I got a green card now.

CARLSON: Oh, you do have a green card.

VARGAS: Yeah.

[...]

We're all Americans.

CARLSON: No you're not actually, you're a Mexican citizen I believe.

VARGAS: A Mexican-American and that's the pride of this great nation.

CARLSON: You know what you are, you're bold.

And we all know what you are, Tucker. And you're paid to be that by Fox News and applauded for being that by your audience of racists and bigots.