From what I’ve seen, most LE go by a playbook that has been born out of the experiences and best practices of other LE. (When an incriminating dashcam video of police activity comes out, note how often you hear a police chief say, “I Watched the video and was disturbed by what I saw” in almost always those exact words - because they’ve found from watching other LE do it, that it is effective in appeasing the public).
They used to be pretty specific in calling out people as POIs and saying who has been cleared and who hasn’t.
But they had some bad experiences with saying someone was cleared who ended up becoming a suspect, or vice versa. And at some point they talked amongst themselves and said, “You know what? We have nothing to gain by painting ourselves into a corner. Let’s just keep things generic and say things like ‘we’re open to all possibilities and we are not naming a suspect or POI at this time’. Then surprise, a short time later they make an arrest.
I don’t blame them - I would do the exact same thing.