People find security in boundaries, security, and predictability. I have found those values actually masquerade for much of what is described as moral. People may say "stealing is always wrong". That implies that they will never be in a situation to challenge that. It means life is safe. They know exactly how to behave and choose, and they will never have to feel guilt unless they clearly make a wrong choice. Sometimes it has nothing to do with stealing, but everything to do with security. The types of issues you raise would shake many people's assumptions, so they will resist it. It's easier to just place your relativist ideas, and possibly you, outside their world view and understanding, rather than trying to reconcile what you might mean, and how honest reasoning could actually be behind it. Dismissal is another way of expressing predictability and security.