Well I mean in many countries, blocking the surveillance agency from listening in on your calls/texts/chats is illegal. So making an app that interferes with the agencies ability to "listen in" is infact a criminal enterprise.
How about adding "illegal thoughts" to that mix too. It is only one short step away from wearing a monitoring "headband". All subversion grows its first root in the mind of the citizen. Nipping this in the bud through detection and re-education guarantees peace and safety of society and the nation. If you have done nothing wrong, you have nothing to hide.