The Doctor was only obtuse when he wanted to be - he was able to catch the double meaning of River's 'sting' remark, and the corner of his mouth quirked, wryly. He reached out for the glass and took a swig, then tipped his head back to gargle the brandy before swallowing.
He then looked at River, knowing she wouldn't accept any bullshit. He sighed and said, "Remember when you became Mels, Handy became a Time Lord, and the Master turned into Missy? All these weird changes happening to people? There was somebody on the Network who wanted people to sign in and say what happened to them. I didn't respond, but I was lying. Something happened." He scratched the corner of his eye, nervously. "I gained future memories," he said, lowering his voice. "And it was too much."