I am admin, and the funny thing is that the choice disappeared only in the backend. If I use the toolbar through frontend edit, I still have 'product' listed there!
The class exists and also rm -fr var/cache; rm -fr var/ezwebin_size/cache didn't help...
I installed different shipping modules (fedex, etc) and uninstalled them, probably this is a sideeffect of playing around with these contributions. I'd like to fix the problem although, because this is going to become a production site.
I'm going to have a look at the rights, but since the choice is in the frontend, I don't believe it's a matter of rights...
In the admin page, it says it was already assigned to Content. So I also assigned it to Media, so that I could remove it from Content. Then I placed it into Content again, then removed it from Media.
Same as before, it doesn't show up in Content, although it says it belongs to it!