For all his harshness, Kenshin knew that the boy's heart was in the right place but rushing at Raijuuta wasn't his brightest idea and he wasn't about to let him have that fight.
He understood his anger, he raged silently when Megumi had told them the extent of Yutaro's injury and he wasn't about to let it happen to Yahiko as well.
Kaoru saw him off with worry- dark eyes. That was all the more reason to catch up with Yahiko.