People who are suicidal with a plan are not generally thinking clearly and are happy that they received care once they've been treated. We take people who are acutely intoxicated or unconscious to the hospital all the time and have no qualms about that.
Regarding being "pumped with drugs", I can only speak from experience rotating for 6 weeks at two different psych hospitals, but the only people who I saw forced to take medication were acutely psychotic, manic, or incredibly agitated. The schizophrenics that are picked up and brought to psychiatric hospitals generally are so psychotic that they would not be able to care for themselves - risk of harm to themselves. Same thing with acutely manic bipolar patients.