it is correct. A player cannot be offside directly from a goal kick.
I learnt this when playing. There was a team in our league whose strikers used to line up on the edge of our penalty area when they had a goal kick. First time we played them, we lined up around the half way line only to find out the keeper had a mammoth kick that sailed over all our heads. We all called offside and the ref informed us of the rule.
Fortunately the striker was rubbish, couldn't control it and it went through to the keeper. Used to hate playing them though. Having to win headers on the edge of your own penalty area from a ball that's travelled 80 yards was no fun.