What they're having you do is work each shoulder separately. Very often they're done at the same time with a strand of yarn for each.
When you work the first row (the bind off 8, leave 12 on the needle,) those are the stitches for one shoulder. It's not really a short-row technique, you're just holding the stitches on the needle to be used later.
You bind off in stages so the shoulder has a slight slope to it.
Since you can't bind off at the end of the row, the shoulders will be off by 1 row. Every sweater with a shaped shoulder is like this, and it doesn't make a bit of difference. It's necessary to bind off on different rows so you can bind off at the beginning of the rows.
Just follow the directions as written, and you'll be fine.