His temper does cool down on the walk. Meaning he's not running hot by the time they make it back into the 'kitchen'. That does not mean he's not angry.

And t doesn't really change his plan.

For one thing he told Zerxus he wouldn't get so attached that he wouldn't take opportunities he saw. That Zerxus meant escape/leaving him isn't really a huge factor here. For another, he really feels like knowing exactly what will happen at a display of both disrespect and resistance is something he should know.

...And, of course, he just wants to.

So, he pretty much gives Zerxus just enough time to get out of his way.

"Hey," in reply to the welcome back. Then throws a punch.