Decreasing profit 10-20 cents is not the same as a 10-20 cent loss on a song, unless you are making the assumption that someone would have bought the song at either price point. The poster my comment was directed was implying the break even price is in the neighborhood of 79-89 cents and that selling at 69 cents is a 10-20 cent loss. I think the break even is actually lower and that by decreasing the price to $.69 Apple would still turn a profit, meaning that they wouldn't "lose" 10-20 cents on that song unless the buyer would have bought at full price.
For example, lets say the profit is .50 per song and they sell 1 million a month. Total profit is 500,000. Reduce price to .69 and now profit is only .19, but if that increases sales to 5 million a month, they make 950,000 in profit.