If the strainer bowl is empty with no water in it, there is nothing to freeze. You are good to go. If there are a few drops of water still left, there is plenty of room for expansion. Living outside of Orlando, IF we get a freeze warning, I just drain the block, trans-cooler line, freeze plugs, water line to impeller and strainer. I have never done the anti-freeze protocol.....it always warms up in 2 or 3 days and we are skiing again!
Based on the above sequence, it appears Chris is "flushing" the engine block with the anti-freeze solution, then draining that solution. Once the engine has been rinsed with the solution, you can drain it, then put the plugs back in.
If the block is drained and all points are properly drained, there is nothing left in the engine to freeze. I suppose if it gets cold enough, (below the freeze point of the anti-freeze/water solution) that could freeze. If there is no liquid in the block, there is nothing to freeze.