Swing hard at pitches you think you can hit hard, including the ones with 2 strikes. With 2 strikes, also make contact on borderline pitches/good pitches by the pitcher which look like they may be strikes. That's a good idea, if that's what he meant, that's normal sound baseball.
If he's saying choke up and put the ball in play, to ignore the opportunity for a long-ball on 2 strikes, I disagree with him.