What this suggest is that at times when BCC is more profitable to mine and the hash rate migrates to BCC, the average block time for BTC will increase significantly and BTC's already slow and expensive transactions will become much more so.
"Profitable to mine" means you have to have buyers. If you haven't noticed, everyone is trying to dump their BCC (BCH? whatever) at any price and trade for more BTC.
Yes, if the price the BTC miners could dump for remains below the cost of production of Bitcoin Cash coins, they would not mine it. Miners want to earn profit, not make a loss. I think you may have misread what I wrote because that's what I'm saying.