I cannot speak to the underlying law, but from a practical standpoint - I (and my sis) had to involuntarily my mom (bipolar and waaaaay off the reservation) several times.
While my father was alive, it was a bit easier as they certainly took at face value the statements of the man living with her, coupled with her behavior.
After he passed, it became much more difficult, as the bias was certainly against sis and I, who were more likely to be seen as trying to put inconvenient mother into the hospital, presumably so we could raid her assets.
Anyway, in talking to an eldercare attorney, his suggestion was to go swear out (I don’t recall the exact language) a warrant for observation, at the circuit court, who would then engage the cops to go pick up the individual, take them to the nearest hospital for observation. I believe that the warrant issued by the court for observation satisfies the rules of the 4th amendment. But I’m no legal scholar.
BTW, we never went that route with my mom, we handled it the hard way, as I was not really interested in Baltimore city cops showing up at my moms place.
The people swearing out a “warrant” as to the possible dangers posed by Mr. Raub had nothing but a few internet postings that may suggest (if interpreted loosely) he is a danger to someone.