True, if something like that is in the vicinity, not good. But with a cable like suggested, you you make it harder. I am thinking in the workplace.
Edit: Also, communication could be encrypted. The receiver could show a QR code with a one time key, which your phone recognizes and encrypts with.
Not to mention simple analog channels vs complex modern protocol.
Eq. it's unlikely the computer will try to take over your mobile device over an analogue audio channel while there could be viable attacks over an USB connection.
