I completely understand your point. I just can't imagine a scenario where some state authority takes the time to look at your phone and then:
- gives you a bad time if they see the word Riot.im on your phone
- or, lets you go about your business if they don't, or sees [generic chat app name]
If someone is intent on abusing their authority, then they will abuse it. There's no reason [generic chat app name] won't become the new "evidence" for tomorrow's abusers, even if it does accurately describe the app's function.
I appreciate the argument about not giving them cause to abuse their authority. But, as you say, if simply standing in the wrong place at the wrong time is enough cause, then it is completely impossible to stay safe by keeping a low profile. The system has been designed to give citizens little control and blur the lines of criminality.
edit
I want to clarify that I don't want anyone to suffer, especially over something as mundane as an app name. The realist in me is happy for any measures to prevent abuse to happen. The idealist in me finds it disheartening that the motivations of abusive regimes and cynical legal systems even have to be given a moment's thought.