Looking at the actual text of the law, I think your 'shoulder holder' is going to get a ticket, too.

"(2) A person commits the offense of driving a motor vehicle while using a mobile electronic device if the person, while driving a motor vehicle on a highway or premises open to the public: (a) Holds a mobile electronic device in the person’s hand; or (b) Uses a mobile electronic device for any purpose."

(d) “Using a mobile electronic device” includes but is not limited to using a mobile electronic device for text messaging, voice communication, entertainment, navigation, accessing the Internet or producing electronic mail."

https://olis.leg.state.or.us/liz/2017R1/Downloads/MeasureDocument/HB2597/Enrolled

Notice that you can get the ticket 'in premises open to the public'?  Like driving through a parking lot!  

There is an exception or two "(i) Is pulled over on the side of, or is pulled off, a roadway; (ii) Is in a designated parking space;"