His point is not that trade deals are bad, but that bad trade deals are bad. This is how he couches his condmenation:

“NAFTA was sold to the American people with promises that it would grow the economy and create millions of new jobs. But today, we know those promises were empty,” he said in remarks prepared for delivery at a town hall forum in Derry. “In all three countries, it has hurt workers and families while helping corporate insiders.”

…….

“The folks in Washington say that trade is good for the economy, even if it hurts a few ‘losers,'” he said. “That’s the word they use, losers, and it tells you something about how they see regular American workers and families who are struggling to compete.”

This attitude on trade deals ties into an attitude of, “What’s good for Wall Street is good for the country,” which the has led to many of the problems we see now (housing crash, credit crunch, etc.)