Taako gives a short "hmph," and he does drop Foster-- rather suddenly, in fact. It's only about two feet, but he's making a point.

The point being that Foster is being an ass, and he's not going to put up with it.

"Alright, first off, who the hell is Sans? Because nobody put me up to anything, my man. I'm just giving you a hard time because you were a fuckin' rude dude just now." Taako props a hand at his hip, the other leaning on the Umbra Staff's tip. "Second, neither do I, I just didn't want you to ruin the party."