He's talking about a time period when the stock market was in the doldrums and inflation was high. Right now inflation is considered high (even though it isn't really, historically) and the stock market is berserk.

And why wouldn't the stock market be considered a valid investment in the presence of inflation? Where else are you supposed to park your cash if you want to outperform TIPS? Remember that in the 1970s there basically was no retail stock market compared to what we have now, where everyone and their dog has a 401(k) and trading is basically free.

Even if valid, his point doesn't seem relevant. It is going to be hard to apply any lessons from the 1970s to what we're facing now, when incompetent and erratic policymakers are driving the US economic picture rather than external influences like OPEC and Viet Nam. (And if we thought OPEC was a malevolent cartel, just wait'll the rest of the world starts forging its own trade agreements without inviting us to participate.)