Yes, this is why I mentioned muscle preservation and focused on the hormonal impact of different kinds of exercise. The "calories-burned-per-muscle-pound theory" is probably a drastic simplification of the benefits of resistance training. Then again, the article in point shows that muscle mass isn't the only relevant metric - the article shows that changes in muscle quality (becoming more "slow twitch" in character) can have vast health implications. Conversely, it might follow, that nobody needs to gain a pound of muscle to accrue benefits from weight training.