If you've also read one of Sklansky's older books (Theory of Poker), you'll be familiar with the Fundamental Theorem of Poker:
Every time you play a hand differently from the way you would have played it if you could see all your opponents' cards, they gain; and every time you play your hand the same way you would have played it if you could see all their cards, they lose. Conversely, every time opponents play their hands differently from the way they would have if they could see all your cards, you gain; and every time they play their hands the same way they would have played if they could see all your cards, you lose.
Sklansky goes on to define "mistakes" in this literal context - being an action which a player would not make if they could see all player's cards (and understood the concepts of pot odds etc) - with the size/impact of the mistake dependent upon the size of bets being "incorrectly" made or called.
I believe the scenario you describe and the concept given in TaP is more or less a re-statement of the above section of the Fundamental Theorem of Poker, because it is a situation where a player is on a draw (and presumably behind) and so needs to hit a certain runout to have the best hand, therefore also requiring a combination of express and implied odds in order to justify continuing in the hand.
If you bet enough that this player does not have the necessary express/implied combined pot odds to make a call +EV, then by calling your bet they are making a mistake as defined above. It follows that the size of this mistake is directly proportional to the size of the bet they call - the larger the bet they call incorrectly, the larger the mistake they are making and the more you gain (in the long run, when variance is not a factor, rather than each and every time this happens - see Sklansky Bucks).
So yes, if you are 100% sure your opponent will call any size bet with a draw which is behind in terms of EV, it would always be correct to bet all in, with a few assumptions:
- You are playing a cash game: in tournaments, you need to consider ICM and the value of your tournament life, along with a lot of other factors
- You are HU with this opponent: if there are other players in the hand who either aren't guaranteed to call or don't have a hand which is behind to yours, there may be times when it does not make sense to shove)
As for your final statement:
I feel that over-betting (and shoving) will eventually lead to ruin, even though each action is +EV.
The only way that over-betting or shoving when this creates a +EV situation will lead to ruin is if you are unlucky. As the number of hands you play (therefore reducing variance) and the relative size of your initial bankroll (larger initial bankroll reduced Risk of Ruin) tends towards infinity, so will your profit.