This is hard. Very very hard. It's the difference between "freedom" and "responsibility".

There is nothing wrong in writing, for example, a software to capture people's faces and detect their ethnicity, but you have to think about what that will be used on.

Even on an open source project, you can take responsibility without blocking people. You can make your project harder for people trying to abuse to use it, to the point they will have to take control of their own fork.

One example is a small application called Tusky, which is "An Android client for the microblogging server Mastodon", completely open source. Mastodon is a network of microblogging servers with connect to each other, kinda like Twitter, but you can pick a different server that is not and still get updates from that server. One of the servers that appeared in the server list is an alt-right server which, as most alt-right forums, promote a lot of hate. What Tusky did? When you try to add an account on that server, instead of adding the account, they play a video of Never Gonna Give You Up, basically rickrolling anyone who, well, is an alt-righter.

Tusky broke the open source license? No, the code is still available. Anyone wanting to use the server can pick the code, fork it, remove the rickroll and release their own version of the application. But Tusky developers took an instead of saying "We'll not take part in promoting hate speech" and one can't deny that they did.

It is a bit hard to do so on the company code -- you would get some reprimands if you try to shame or block one of the company clients from using the company application -- but you can say no and, depending on how offensive you think the use the code is, you can even start looking for a new place to work. People on larger and "cooler" companies, like Google, left their jobs because they didn't agree with what the company was doing, and so can you.