Severus only nodded, though he did smile. Since he'd been told to shut it, answering would have been ... well, what he would have normally done, to be honest, but he didn't feel like trying to get a rise out of Regulus just then. So he kept his mouth shut, up until he took a sip of tea, after adding a splash of milk.
"It's fine," he said with a shake of his head, lowering his cup. And, since he was already speaking anyway ... "Though I won't deny that it was delicious to nettle your cousin the way I did, it was protectiveness, with a heavy dose of loyalty thrown in, for good measure." And even if the tea really wasn't all that good, he took another sip.