"I've been too - ah - preoccupied the last couple of months to pay much attention to the news," Regulus replied. Barty's comment about leaving the past behind was potentially a good sign, but then again, Barty had once been a Death Eater, and Regulus was not inclined to take what he said at face value.
"Why don't you tell me about it, and we shall see?" he suggested. That way, he could learn much from Barty's tone and body language and perhaps discern whether Barty was telling the truth or not.