Most methods of sedation will bring on respiratory depression as a side effect. It's the reason you need to be on a ventilator when you're having anesthesia.
Needless to say, a patient who wants survive what the OP describes shouldn't risk additional respiratory depression.
Disclaimer: I'm no medical expert. I may be talking out of my ass.
Sedation should always be preferred to restraints, but for various reasons it is not possible to sedate someone 100% of the time in the ICU. The use of restraints described in the article is disturbing, but more context would be needed to understand whether they were appropriate or not.
