The FED rule is rather specific...
I haven't got my books but it seems like a scorebook or a PDA (to keep score/batters count) are allowed. I don't believe an indicatorclickertingymabob is specifically mentioned.
But I'm thinking that an indicatorclickertingymabob in the hands of a coach is exactly the right place...
Don't know about USSSA rules but they are probably similar.
But I'm with the camp that feels "Who in the heck cares?"