To give an example of what can go wrong, your description suggests that you just hold the person where they can't reach you and drag them. But if you try that you'll find out the hard way that there is no good way to drag the person while they are still panicking without getting grabbed.
To give another problem, can you swim in place for a minute with your hands out of the water? Try it before confidently asserting that you can. And that is substantially easier than swimming in place, holding a struggling, panicked person up.
Those are among the reasons why I've so strongly recommended that untrained people avoid option #4. If you can stand on the bottom, fine. Otherwise, not so fine.