Scott Houston's role is mainly to be motivational, and to perhaps sell his book. His TV show is what got me interested in learing Piano, and I'm very glad for that. However, you shouldnt confuse it with piano instruction.
I dont know what I did with his book. I havent seen it in a long time. Probably I pitched it in a fit of rage. It is absolutely content free. Absolutely any other book you read will be 100% better, will have some content. For just one popular example, "How to play Popular Piano in 10 Easy Lessons" by Monath is pretty good to explain first concepts. Your public library probably has it. This one is quite overstated too, but at least it actually attemps to explain a few things. Scott Houstons teaching philosophy only seems to be to just "press these little white and black thingies with your fingers". And that is indeed all it takes.
That takes nothing away from the classical vs popular music comparison. They are indeed very different concepts and styles, and not everyone is interested in playing classical music, no shame in that.
The classical piano style learns to play the music exactly as written, no exceptions. This takes skill and learning. You know exactly what to do, the music makes it very clear what to do. The trick is in learning to make your fingers do what you want to do.
Popular is played however you want to play it, no two people will likely play anything the same way. It is mostly chord based, but this is an awesome subject. Not only do you have to know how to decide what notes to play, and then you also have to have the same skill to make your fingers do it.
So, a little classical instruction is a very good thing, a good starting point, even for the goal of playing popular music. There is just a wee bit more to it than Houston would have you believe.