It says in or on, meaning interior or on exterior respectively. 550.32(B)(2) states "The installation of the service shall comply with Part I through Part VII of Article 230."... and what that means is that when installed inside, it must be nearest the point of entrance of the service conductors. Manufacturers usually put the panel in an exterior wall to make compliance easy. Otherwise, the installation would have to consider methods enumerated in 230.6 Conductors Considered Outside the Building.
(B) Manufactured Home Service Equipment. The manufactured home service equipment shall be permitted to be installed in or on a manufactured home, provided that all of the following conditions are met:
Now your being selective it says that the service equipment shall be permitted to be installed in or on (not the grounding electrode conductor) provided that all of the following conditions are met:
article two 230 would allow the grounding electrode connection to the system neutral in the meter enclosure or any place up an to the service drop or lateral article 230 would also allow the connection to the neutral in the service disconnect enclosure.
However article 550.32 Before you are allowed to install the service in the manufactured home you must rout the groundin electrode conductor out side
For example We know that article 230 allows provision for a connection point the easily would comply connect it to the neutral in the meter enclosure
(1) The manufacturer shall include in its written installation instructions information indicating that the home shall be secured in place by an anchoring system or installed on and secured to a permanent foundation.
(2) The installation of the service shall comply with Part I through Part VII of Article 230.
(3) Means shall be provided for the connection of a grounding electrode conductor to the service equipment and routing it outside the structure.
(4) Bonding and grounding of the service shall be in accordance with Part I through Part V of Article 250.
(5) The manufacturer shall include in its written installation instructions one method of grounding the service equipment at the installation site. The instructions shall clearly state that other methods of grounding are found in Article 250.
(6) The minimum size grounding electrode conductor shall be specified in the instructions.
(7) A red warning label shall be mounted on or adjacent to the service equipment. The label shall state the following:
DO NOT PROVIDE ELECTRICAL POWER
UNTIL THE GROUNDING ELECTRODE(S)
IS INSTALLED AND CONNECTED
(SEE INSTALLATION INSTRUCTIONS).
Where the service equipment is not installed in or on the unit, the installation shall comply with the other provisions of this section.