He was grinning against her before going right back to attending to his love's sexual needs - maybe this was the one thing she didn't see coming. His theory was that if he brought her enough pleasure Athena wouldn't be able to focus on anything else including her all knowing badassery so he was about to put this theory of his to the test.
He wanted to make Athena cum before he'd let himself cum for Aphrodite but before they actually started fucking he wanted to have the two goddesses change positions so he could eat Dite out while Athena blew him. They'd both get their own mouthfuls if the winged god had his way - as well as having him playing with both of them at the same time in the same position Athena was in right now before they got to the best part. "Mmmm with such pretty goddesses eager for attention who needs a harem? Not me!"
Athena was all he really needed - she knew this but if Aphrodite didn't feel included she'd be hurt "Don't worry Aphrodite you'll have your turn up here soon enough." If Jon could out pleasure Aphrodite eating out Athena then the love goddess was in for a treat when it was her turn!