bokaman, I don't think he's preaching. In our spiritual community, we dream of utopian like world where everyone lives in peace and harmony. We also don't just sit tight and do nothing. Just turning someone into with realization of spiritual values is like to light a candle and help them get rid of darkness of ignorance. I've personally vowed to do so, I try it, and if it sparks someone's interest I get involved, if not I move on. Just trying to get someone out of unawakened state , to pull the plug off this matrix , I don't think it's called preaching.
Now, if he's marketing here like spamming , I think that's not a good idea but I don't think it's him here doing so. And, his books are not even more than a coffee worth. Why do we have to be so cheap that always look for free stuffs? It's human nature that our mind don't give that level attention to free stuffs than paid ones? anyway, your logic, your choice but to me, it's not preaching. Paying for his book is like going through one of the karmic experiences to read what his views are.