Are kindness and preparedness mutually exclusive, or is it possible to be civil while also remaining vigilant?
You'll note that I did not disagree with the statement I quoted, only pointed out that one must keep in mind that predators are aware of how people want to behave, how they want to see themselves, and are known to use those desires as a weapon.
Automatically being dismissive or curt toward anyone I don't immediately recognize would reflect poorly on my company and ultimately negatively impact my livelihood.
I haven't told anyone to be automatically dismissive or curt. The specifics of how one deals with the awareness that their own desire to be kind and polite can be used against them to gain an advantage will be a personal decision and will depend heavily on their own circumstances and on the circumstances of the encounter.
Thinking there has to be balance.
Human interaction is complicated. I don't think it's possible, in general, to boil it down to a simple rule that will work in all circumstances. But remaining aware of potential danger is important. Knowing specific methods predators might use to gain an advantage is important. How a person balances that awareness with their own personal circumstances will vary from one person to another and from one situation to another.
The concept of competing motivations is not peculiar to this topic. We often find ourselves in situations like that. Such as when a spouse asks us a question where the desired answer is clear and giving it would be kind even though it is not really accurate--we want to be nice, to reinforce the person but we also want to be honest. What course of action should be taken? Depends on the circumstances. Responding "kindly" to "How do you like my new hairstyle?" doesn't have the same potential for a really bad outcome as being too nice when the same person asks if they should worry about a large, multicolored mole with ragged edges. Sometimes honesty is very important, sometimes, not so critical. But one needs to have the proper information to make such decisions. A person who doesn't know about the warning signs of skin cancer might think the question about the mole was just the same as the one about the hairstyle, while someone with that information would realize that the two situations are very different.
Same thing here. The important thing is understanding the situation. If you are aware of the potential for danger, then you have a chance of reacting appropriately, of choosing a course of action, of finding the correct balance.