Nice one! Been hoping for an interview with him for a while, but never got round to it.
Either way, nice to hear his thoughts on the game and the book, and I hope to see him cover some of the other Wario games in future.
Edit 2: Also, the 'getting stuck by doing insane things' concept is common enough to be on TV Tropes:
http://tvtropes.org/pmwiki/pmwiki.php/Main/UnwinnableByInsanity
As a series (not just as a game even), the Wario Land games are great at making sure you really, really can't screw yourself over in any real way, at least not that I can think of. But as Daniel said, you've got to keep in mind these issues are only an issue if you're really thinking outside of the box and trying to break the game on purpose. I mean, I got trapped on a tiny balcony outside Treacherous Mansion in Luigi's Mansion Dark Moon... but given that I had to glitch the game to get there in the first place... it was best not to hold it against Next Level Games.
Edit 3: Wario Land 3's system is why I love the 3DS save state functionality. Makes these soft challenges a whole lot more fair.
Edit 4: There are ten treasures in Virtual Boy Wario Land, so probably not. He's been on at least one adventure off screen.