Is there a way to add bulk operation options to the admin/content list's 'Update Options'?
Bulk operations provided by that module only make sense in the context of a view, so you won't see them on a non-view page like the standard admin content page.

You can install the Administration Views module to replace that page with a View, and then you should see the options you're expecting. Most (all?), of the core actions from the original page should be available. To add more, you can edit the View and change the available actions in the VBO field.