His point is that what has been demanded of Greece - austerity - will only make their recession worse, but to not demand it would be to let Greece continue to spend way beyond their means. We have aging populations with social security and medicare costs going through the roof. Governments have promised too much without the revenue means to fulfill those promises.
Actually, Samuelson does a good job with the article as far as it goes. What he doesn't do is tell us how to get out of the mess into which we have drawn ourselves. He doesn't specify the unpleasant steps to fiscal solvency: either less spending, or more taxes or possibly both.
Nobody knows how to do these things in democratic societies where what is popular is more benefits and less taxes; what is unpopular is less benefits and more taxes; and what is popular is what gets a politician reelected.
