Drain the squash, reserving the brine. In a medium bowl, toss the cabbage and kale with the 1 1/2 teaspoons salt and massage, squeezing, for a minute. Let stand for at least 15 minutes, then massage and squeeze again, the leaves give off liquids when squeezed. Rinse with cool water and wring out the shreds and put in a bowl with the drained squash slices.