As far as Ron was concerned, Malfoy would have to ask Harry if there was anything he could personally do to help them. Especially now that people like Pettigrew was coming back, but that would be something Ron brought up with his best mate, not Malfoy.
When an apology came, Ron could have been easily knocked down with a feather. The last thing he’d ever expected was to hear that Malfoy was actually sorry for something.
“You’re lucky you didn’t kill me actually or I would have come back and killed you personally,” Ron said in his own way of accepting the apology.