Rodolphus pretty much ignored Lucius. He had been chided by his friend for not protecting Rabastan and now he was being chided for doing it. Either way he had to admit Lucius was right it was up to Rabastan. He got what he wanted out of his actions. Rabastan knew his big brother was there and would protect him, if he wanted said protection.
When Rabastan decided to continue Rodolphus took a step or two back. It was his way of giving his brother room. It was an unspoken way of saying you are not a baby you can stand on your own two feet, but should you start to fall I will be close enough to catch you. "That is your choice little brother" He said nearly expressionless, as he caught the shirt that was thrown at him. "I have no doubt you will" He replied to his brother assertion that he would find his robes first, and then he caught the trousers that were tossed at him. "Well you better get looking if you want to be first" He added, more to get Rabastan away from Lucius and the fire whiskey than anything.