You're right. In that context, it can definitely be bravery.
However, in general, the decision to answer or not answer a salesperson at your door is not about bravery. It is primarily about effort and annoyance.
The combination of "Is it really that hard to say "Selling something? Not interested, have a nice day!"?" and a condescending "Gotta be brave and interact with the world sometimes." rubbed me the wrong way.