I think it's more nuanced than naivety. Germany was willing to turn a blind eye for the cheap energy their powerful industrial economy relies on. I don't think it's wrong to take the cheap energy knowingly from your enemy -- you just can't lose sight of it.

Fundamentally it's ok to arbitrage with your opponent if it means more prosperity for you -- it gets complicated when you're doing it on the back of large deficits, and do it for long enough that you forget it was a gambit to begin with and now it's a dependency. Oops.