I started off with QBASIC on an Atari400 when I was 11, based on a single book. Had a lot of fun. That's great that it worked for you and I - we happened upon our passions. Many people, however, need to be shown things until they find their passion. For many (most?!) of the kids Sandy will be teaching, programming isn't going to be it. However, there may be one or two kids who just completely latch on to the experience, not having seen it before (or not having had the opportunity to try it before). And that's exactly the reason why we expose our kids to various things - to help them find their passion.
Kids who find their passion on their own, that's great. But why leave such an important thing as "the rest of your life" to chance like that? By all means, don't force them into something (well, not for too long - sometimes doing what you don't like builds character, and that's important, too). Expose them to it.
I suppose one of the biggest things I've learned in life so far is that everyone learns differently. Some kids seek out their passion. Others need to be exposed to something before they discover it. Some find a passion, then change their minds a few years later. None of these are bad - they just are.
Intro classes are great - you'll find 50% of the kids don't continue in it (that's good - they've been exposed, and discovered it's not their passion, so they can continue looking), 30% will like it enough to try a second class before discontinuing, 20% may go on a bit further, but never develop a career out of it, a few may go on and make it into a career, and maybe one or two will find it to be their passion. All of these, that is what makes what Sandy volunteered to do worthwhile. Including the ones who don't pursue it. They may think it's dumb today, but 15-20 years from now, they'll look back and be glad that not only they took the course, but that they didn't pursue it. :-)