worldpilot, I think you have a mixed understanding of the requirements. An Instructor cannot sign the ratings revalidation page only an examiner can.
It is perfectly acceptble to do the 1hr flight with an Instructor who is also an examiner and they can than sign the revalidation page which is what I do.
To be clear you can do the renewal by experience in 2 ways:
1hr flight with an Instructor, he signs the logbook to say verify the flight has taken place.
You take your licence and logbook to an examiner and he signs the revalidation page.
Or:
You come to someone like me who can conduct the 1hr flight and then sign your licence and logbook in one sitting.
It is accepted policy that an examiner signing a revalidation page will be looking for a signed PUT entry of 1 hour or greater as a single flight with an Instructor. The Instructor signing the logbook is just a way of the examiner seeing that the flight was real and not just an entry made up or entered incorrectly.