I mean yeah, but you buy White Day gifts as thanks for the Valentine chocs, no? If Kaname, Ran and Sensei don't give him chocs he has no obligations to buy WD gifts for them.
On second thought, maaaaybe Sensei gave him courtesy chocs and he'd get her WD gift, and if the 1st Valentine chapter is any indication he buys WD gifts for even those that didn't give him any (Reiko). But unlike Sensei and Reiko I don't think Ran and Kaname are close enough to him that he'd give them WD gifts (considering he outright fears the latter and all)