Be that as it may, it's their property and their rules. If a person wants no weapons on their property, that's their right.
It is their right... which is why many states have provisions for approved signage that stores/restaurants/etc... can put in a conspicuous place at their entrance (that carry some legal weight) to notify people that they can't carry inside the establishment.
So there's two aspects at play here...
1) Whether or not ambiguity favors permissive over restrictive (which in most cases, it typically does -and should)
2) Practicality
(Obviously courts are going to focus on #1 primarily)
Think of it sort of like parking regulations. If there is a parking lot, and there's not any sort of "No parking" sign visibly posted, would the reasonable assumption be, "it's fine for the public to park here", or would the person be calling the entity that owns the parking lot ahead of time to ask "Hey, I notice there's this parking lot next to your store, there's not any signs saying I can't park there, but I just want to make sure I'm allowed to park there"
In terms of the practicality aspect -
Not every public facing business has an owner on-premises or that's easily reachable for questions.
While some of your smaller mom & pop places maybe the sort of the environment where the owner is on-site and easily accessible for questions, what about the major chains, franchises, or businesses that lease space from a property management company in a shopping center?
In the case of a Target, Walmart, etc...
The person "in-charge" at the store isn't the property owner, in many cases, they're several layers removed. It's an assistant manager, who rolls up to a store general manager, who rolls up to some regional director at corporate, who rolls up to a CEO, who rolls up to a board of shareholders who collectively co-own the enterprise.
So if Target didn't have any clearly posted signage indicating one way or the other whether or not concealed carry was allowed, who exactly would a person reach out to in order to get that clarified?
In the case of a business that's leasing space. The owner of the business says "I don't want any guns in here", the property manager says "yeah, it's fine, you can carry on the property" -- who wins out?
Ultimately, I'd say if Hawaiian businesses want to forbid CCW holders from carrying on the premises, they can hop on any number of online vendors, and order a state-verbiage specific 4 pack of "gun busters" stickers for $3.95 just like every other business does in the other 49 states. Or the state of Hawaii can make free to any business who wants one if they're really doing this for the business owners (and it's not just a bunch of legislators trying to make a right they don't like more cumbersome on purpose)