Without commenting on the rest of either of your posts, he is talking about how to trade between stable and other coins with that limit on Bitcoin. i.e. He is saying there will be so many people trading away stable coins for Bitcoins (as in Bitcoins not generic stand in for cryptocoin) or other coins that the 7tx/s limit of Bitcoin wallet transfers that it will become a significant factor as Bitcoin is used as a 'reserve currency' for these trades.