Is your concern how you treat those specific individuals who have demonstrated their beliefs? Or is it about pre judging future people who you will meet? The answer will look different.

If it's about those particular dudes... consider learning more about them and showing them more about you. It may be powerful. If that puts you at risk then don't do it. You are under no obligation. They already showed you who they are.

If it's about others... have you already find yourself demonstrating prejudice? Had it happened yet, or is it just a fear? Biases are natural. Everyone has them. Recognizing them is the greatest defense. Huge. Stereotyping is a protective mechanism to help us figure out what is safe or important. It is a shortcut. It cuts down mental processing time by seeing not just a new individual sensation but also a thing that is part of a group that already is in a mental network with a web of associations. You learn more on an instant than you would by investigating every new thing. Even if it's not perfectly accurate, it's good enough for spotting tigers and strawberries.

Biases are shortcuts. But not everything deserves a shortcut. Getting to know another person sometimes means taking the long road.

Don't feel ashamed that your mind wants to take shortcuts. It might help you feel safe. In a fraction of a second your brain might think, "He looks a lot like that guy that said he would hurt people like me." But part of being human is being able to rise above that. Stop and think: is that the same guy? No. Let's give him a chance and see what he's about.

Or don't. Stay safe. The risks of human relationships can be rewarding, but they are still risks.