Saying the "kids" used his computer for downloading music doesn't imply that ALL his kids used his computer for the internet AND Ed specifically said ES didn't use the internet. There is nothing contradictory about that.
Try this. Draw a circle on the left side of a piece of paper and label it "Smart Kids". Draw another circle that overlaps the other one part way on the right side and label it "Internet Users". The Smart children that "use" the internet are in the overlapping portion of both circles. The other Smart children, including Liz, that don't use the internet are in the other part of the Smart circle that doesn't overlap. The remainder of the Internet Users circle depicts the remaining hundreds of millions of internet users (including you) who don't belong to the Smart family.