Before you boycott, try going up the chain of command.
Call the store tomorrow & get hold of the store manager.
Tell him what happened, & that you understand Cabella's corporate policy is to welcome lawfully-armed customers, so you're confused by this person's comments/directions. (As well as being offended.)
Let the manager tell you that they follow corporate policy & that s/he will reeducate the underling.
IIRC, you could also submit a comment through the Cabella's website.