I worked for a company that made deep packet inspection based network equipment. Western customers mostly used it for "security" and media streaming man in the middle attacks (actually a useful feature saving lots of bandwidth). The boxes were also sold to Syria and Burma, and were used to facilitate censorship and human right abuses
Ultimately you are like a kitchen knive maker whose knive was used in a stabbing. It was entirely the stabbers fault and does not diminish the utility of your product. In a corporate setting, mitm'ing TLS and blocking sites by category is routine practice (better ways to stop bad stuff but expensive firewals are a waste when most traffic is TLS).
There's a difference between selling knives to the general public, vs seeking out violent criminals and specifically marketing your knives to them.