I don't own LoR so I can't read the quest rules directly, but in general you are correct. If the quest rules do not define these tokens as figures (or otherwise state that the tokens block movement) then there's nothing to stop an ogre from standing on top of one.
The familiar rules have nothing to do with this, though. Objective tokens are not familiars. The reason an objective token doesn't count as a figure is because it's not a plastic figure. There are no rules in the book that define an objective token as a figure, so unless specific quest rules say otherwise, an objective token is a token, physically, not a figure.
As to whether or not you need to defeat the ogre before doing whatever the quest requires you to do here, that would depend on whether or not you are allowed to do your thing from an adjacent space. If you're allowed to do your thing from an adjacent space, then all you need to do is get adjacent to the token (and the ogre on top of it) and you're good to go. If you need to do your thing from the same space the token is in, then you would have to defeat the ogre (or at least move it) since standard movement rules prevent you from occupying the same space as the ogre.
Edited by Steve-O, 16 October 2013 - 06:40 AM.