I agree with what you are saying regarding arrest and custody.No. Absolutely not. Again, this has nothing to do with verbal classifications. It has only to do with custody. Miranda Rights are about custody!
And of course, an arrest also triggers Miranda Rights. This goes without saying. A person placed under arrest is obviously, and undoubtedly, in custody.
Being arrested triggers that the person arrested is in some sort of trouble. There is nothing official about being called a suspect. The term doesn't trigger any new rights, and has no effect on the ultimate outcome of the case. It wouldn't matter if that same person placed under arrest were called a POI instead of a suspect.
But if someone is arrested they are a suspect or a defendant not a POI anymore.
I don;t recall ever seeing an arrested suspect termed a POI.
jmho of course!