It is possible that the officer will testify that you were illegally parked in violation of the "NO PARKING ANYTIME" or "EMERGENCY PARKING ONLY" signage/restriction pursuant to CVC 21718(a). If that is the case, then your argument that "21461(a) does not apply to acts constituting violations under Chapter 9 (commencing with Section 22500) of this division or to acts constituting violations of a local traffic ordinance adopted pursuant to Chapter 9 (commencing with Section 22500)" will not get you very far in light of the fact that 21718(a) is not part of Chapter 9 (commencing with Section 22500).
No person shall stop, park, or leave standing any vehicle upon a freeway which has full control of access and no crossings at grade except:
(1) When necessary to avoid injury or damage to persons or property.
(2) When required by law or in obedience to a peace officer or official traffic control device.
(3) When any person is actually engaged in maintenance or construction on freeway property or any employee of a public agency is actually engaged in the performance of official duties.
(4) When any vehicle is so disabled that it is impossible to avoid temporarily stopping and another vehicle has been summoned to render assistance to the disabled vehicle or driver of the disabled vehicle. This paragraph applies when the vehicle summoned to render assistance is a vehicle owned by the donor of free emergency assistance that has been summoned by display upon or within a disabled vehicle of a placard or sign given to the driver of the disabled vehicle by the donor for the specific purpose of summoning assistance, other than towing service, from the donor.
(5) Where stopping, standing, or parking is specifically permitted. However, buses may not stop on freeways unless sidewalks are provided with shoulders of sufficient width to permit stopping without interfering with the normal movement of traffic and without the possibility of crossing over fast lanes to reach the bus stop.
(6) Where necessary for any person to report a traffic accident or other situation or incident to a peace officer or any person specified in paragraph (3), either directly or by means of an emergency telephone or similar device.
(7) When necessary for the purpose of rapid removal of impediments to traffic by the owner or operator of a tow truck operating under an agreement with the Department of the California Highway Patrol.
(b) A conviction of a violation of this section is a conviction involving the safe operation of a motor vehicle upon the highway if a notice to appear for the violation was issued by a peace officer described in Section 830.1 or 830.2 of the Penal Code.
If that is the case, you're free to argue:
I) that you were not parked on the freeway per se, but on the "off ramp" from the freeway, but that will depend on whether the off ramp is considered as part of the freeway (I honestly could not definitively say either way)... I would assume that if "Emergency Stopping Only" signs are posted on the off-ramp or not... I checked the CA Supplement to the MUTCD and could only find a single reference to 21718 wherein it states (page 2B-37): "CVC Section 21718 prohibits the stopping, parking or leaving of any vehicle upon a freeway. Large NO PARKING ANY TIME (CA Code R26) or EMERGENCY PARKING ONLY (R8-4) signs may be installed on freeways which have full control of access and no crossing at grade to inform traffic that stopping, parking or leaving of any vehicle upon a freeway is prohibited."OR...
II) that you found it necessary to stop due to the fact that you were tired and in an effort to avoid injury or damage to persons or property (as per sub-paragraph (a)(1) above), but that will depend on the court's interpretation of "When necessary to avoid injury or damage to persons or property". In other words, you could easily have driven past the off ramp and onto a surface road/street or to a parking lot nearby.
Your best shot at finding what/how the officer will testify at the TDN would be to contact the court and request a copy of his TBD declaration, as it is highly likely that his in court testimony will mimic what he may have written in his declaration.