[If they had just given it to him, it probably still needed time to work. He knew Keith would ignore pain and keep going, but he shouldn't in this case. He needed to rest it so the nanomachines could do their job and patch up his arm. If it hurt, he might move it too much just trying to get comfortable.
Shiro hesitated a moment then gestured - with his human hand - in the direction of the apartment so they can head back]