As @Fabrice Henrion said, rules does not apply to superuser (i.e. Administrator).

Nevertheless, you can change the action called by the menu "Notes" adding the desired domain, and in that way, the domain will be ensured.

The domain to add is:

[('user_id','=',uid)] 

This can be achived in and `XML` file:

<record model="ir.actions.act_window" id="note.action_note_note"> 
     <field name="domain">[('user_id','=',uid)]</field>
</record>

Or this can be done from inside the system (you have to enable Technical Features first to see the menu):  <I tried to mebed the image without luck...Click to see image>