Trade marks and copyright in book series titles: second opinion sought

A distinguished member of the Spicy IP blog team has written to the IPKat and his readers for a second opinion. The question raised is this:

"In my hypothetical, there’s a book with the title ‘X’, written by an individual ‘A’. The book is a part of a series; the books in the series retain a common “work title”. The owner of the copyright also claims a trade mark in this work title.

If the book falls into public domain following the expiry of the copyright in it, is the owner of the trade mark entitled to assert his right in the trade marked work title? Or can it be argued that the use of the trade marked work title falls within the scope of a meaningful reproduction of the work, which is now in public domain, by another publisher?

I am of the opinion that, since the work title was never copyright-protectable in the first place, expiry of copyright the work does not affect non-copyright elements of the work and the TM owner can therefore assert his trade mark rights without attracting allegations of perpetuating his copyright through the trade mark".

The IPKat agrees with his spicy colleague that the assertion of the trade mark right cannot be regarded as a perpetuation of the copyright. Do readers agree?