He has his doubts about whether Bucky will throw up or not but Steve isn't going to be unhappy about it. He can understand not wanting to show weakness around a slave master. He hates seeing that dead look in the man's eyes but there isn't anything he can do about it that he's not already.

Steve presses his lips together, "No, thank you, that's unnecessary." He doesn't mistreat slaves in any fashion and particularly not when it involves sexual favors.