It actually is a crime if you ignore the sign, and you can get charged with misconduct with a firearm and/or tresspassing, since they made it clear they did not want you in their business with a firearm. However, if you actually conceal it, they will never know, but you're still breaking the law technically.
An interesting point about these signs. They have to post 2 copies. One at all entrance doors and a 2nd by the liquor license. You are allowed to enter, with your firearm, for the purpose of checking if the 2nd sign is posted correctly. If it's not, then you are good to go. One thing about this, if you're open carrying, expect to be asked to leave anyway.
Nonsense.
The operative law is ARS 13-1502A
13-1502. Criminal trespass in the third degree; classification
A. A person commits criminal trespass in the third degree by:
1. Knowingly entering or remaining unlawfully on any real property after a reasonable request to leave by the owner or any other person having lawful control over such property, or reasonable notice prohibiting entry.
2. Knowingly entering or remaining unlawfully on the right-of-way for tracks, or the storage or switching yards or rolling stock of a railroad company.
B. Criminal trespass in the third degree is a class 3 misdemeanor.
The operative words are 'reasonable request'. Your interpretation would mean that you could be ARRESTED for walking in to a 7-11 barefoot, if they post 'shoes required' on the door, or arrested for bringing in your dachsund when it's posted 'no dogs'. Such signs on non-Title 4 businesses ("shoes required", "no pets", "no firearms", etc) are advising you of terms of entry, but you are not trespassing until given a reasonable request to leave, since the signs are not 'prohibiting entry' to the business in general.
There is nothing in ARS 13-3102 (Misconduct Involving Weapons) that covers what you are saying. I'm not sure where you got that from.