Sidon didn't even have a chance to fully register that Link'd had a sister and somehow nobody had ever told Sidon about this before Link's obvious diversionary tactic gave him a moment of whiplash.
There was a lot of whiplash going on in the Domain, and it was finally hitting Sidon. Of course it'd be Link that would drag him into it.
But since this sister obviously wasn't something Link wanted to talk about at the moment, Sidon let it go and gave Link something of a scolding look. "Perhaps I have said that too much. You seem to be letting it go to your head."