I split this post into a new topic so we could keep the open-carry bill discussion separate.
This is a tough issue and would be an excellent law school exam. The short answer is I cannot give a clear cut answer, but here are the issues. As you noted, TPC §30.06 applies only to a CHL carrying under the authority of their CHL. If you are not carrying under the authority of your CHL, as with the Motorist Protection Act or with the gun in the trunk, then arguably TPC §30.06 doesn't apply to a CHL with a gun in their car in a parking lot.
But if you are not carrying under the authority of your CHL, then TPC §30.05 becomes a problem. §30.05 cannot be used to prosecute a person carrying under the authority of their CHL, if the sole reason for exclusion is the presence of a handgun. (See TPC §30.05(f)(1)&(2) below.) But if you aren't carrying under the authority of your CHL, then you could be prosecuted under TPC §30.05, if you had notice and if the gun was on or about your person. (The gun is "on or about your person" if it's anywhere in the passenger compartment, but not in the trunk.)
The question then becomes "does a TPC §30.06 sign also serve as notice under TPC §30.05?" I don't know the answer to this question and I don't know if there any case law on this issue. A 30.06 sign expressly references TPC §30.06 as the basis for excluding the person, so an argument could be made that 30.05 is not being triggered. However, TPC §30.05 does not require any special language; only that the person be given notice that entry is forbidden. Arguably, a 30.06 sign gives such notice.
So I don't believe there is a clear answer to your question; that's why it's a great law school question! (Professors like to see students give a full analysis of the issues.)
Chas.
TPC §30.05 wrote:Sec. 30.05. CRIMINAL TRESPASS. (a) A person commits an offense if he enters or remains on or in property, including an aircraft or other vehicle, of another without effective consent or he enters or remains in a building of another without effective consent and he:
(1) had notice that the entry was forbidden; or
(2) received notice to depart but failed to do so.
(b) For purposes of this section:
(1) "Entry" means the intrusion of the entire body.
(2) "Notice" means:
(A) oral or written communication by the owner or someone with apparent authority to act for the owner;
(B) fencing or other enclosure obviously designed to exclude intruders or to contain livestock;
(C) a sign or signs posted on the property or at the entrance to the building, reasonably likely to come to the attention of intruders, indicating that entry is forbidden;
(f) It is a defense to prosecution under this section that:
(1) the basis on which entry on the property or land or in the building was forbidden is that entry with a handgun was forbidden; and
(2) the person was carrying a concealed handgun and a license issued under Subchapter H, Chapter 411, Government Code, to carry a concealed handgun of the same category the person was carrying.
I support the Fourth Amendment too!