Yes that is exactly what this means. Pre 1.2 mods, ie. Armoring, Mods, Enhancements, do not carry any bonus on the mod. Pre 1.2 shells, ie. Rakata, Columi, Tionese, carry the Set Bonus on the shell itself. This means you can take mods out of Battlemaster gear and slot it in your Rakata gear and gain the expertise stats but still keep the Rakata bonus found on the shell.
Post 1.2 gear with Set Bonus, ie. Campaign & War Hero, do not have the Set Bonus on the shell but rather on the Armoring mod itself. The Set Bonus found on these Armoring mods also overwrites any pre-1.2 Set Bonus. In addition these Armoring mods can only be slotted in like gear, ie. Campaign Chest Armoring can only be moved to a Chest shell. What this means is you can take Chest Armoring out of your War Hero Chest shell and slot it in your Rakata shell and the set bonus will overwrite the Rakata Set Bonus.
Hope this helps.