

Lets talk about principles. If we accept that God sets the
standards for what ought to be included in Scripture - then we
can ask:
1. Is it authoritative?
2. Is it prophetic?
3. Is it authentic?
4. Is it dynamic?
5. Is it received, collected, read and used?

On these counts, the apocrapha falls short of the glory of God.
To quote Unger's Bible Dictionary on the Apocrapha:
1. They abound in historical and geographical inaccuracies and
anachronisms.
2. They teach doctrines which are false and foster practices
which are at variance with sacred Scripture.
3. They resort to literary types and display an artificiality of
subject matter and styling out of keeping with sacred Scripture.
4. They lack the distinctive elements which give genuine
Scripture their divine character, such as prophetic power and
poetic and religious feeling.


But the problem with this argument lies in the assumption that
the Hebrew canon included the Apocrapha in the first place, and
it wasn't until the sixteenth century that Luther and co. threw
them out. The Jewish council you mentioned previously didn't
accept them, so the reformation protestants had good historical
precedence for their actions. Jerome only translated the
apocrapha under protest, and it was literally 'over his dead
body' that it was included in the catholic canon.


How do you then view the words: "I warn everyone who  hears the
words of the prophecy of this book: If anyone adds anything to
them, God will add to him the plagues described in this book.
And if anyone takes away from this book the prophecy, God will
take away from him his share in the tree of life and in the
holy city" (Rev 22.18-9)
Surely this sets the standard and not just man-made traditions.

It is also noteworthy to consider Jesus' attitude. He had no
argument with the pharisees over any of the OT canon (John
10.31-6), and explained to his followers on the road to Emmaus 
that in the law, prophets and psalms which referred to him - the 
OT division of Scripture (Luke 24.44), as well as in Luke 11.51
taking Genesis to Chronicles (the jewish order - we would say
Genesis to Malachi) as Scripture.


I am not familiar with the book. 
Some other arguments you might like to consider are found in
Chapter 3 of Josh McDowell's Evidence That Demands A Verdict.