Post his story in full if you know of where it is ... where he lays out his exact arguments using scripture.
He was raised as a Baptist in Virginia and found Jesus at the age of 10. He loved Bible school. He fell away from the church but as an adult joined the Assembly of God and became well versed in using the tools, as you say, “to interpret Biblical text consistent with the grammatical historical approach using sound hermeneutical principles. He read books by Jimmy Swaggert, Dr. Walter Martin, Dr. R. C. Sproules, went to Bible school and eventually became a youth pastor.
His full story can be found on a CD which costs $20.00, which I would think you probably wouldn’t want to pay. I can share a brief biography and snippets of his story:
http://www.catholic.com/profiles/tim-staples
http://chnetwork.org/2001/05/tim-staples-former-assemblies-god-youth-minister-journey/
http://chnetwork.org/2010/03/tim-staples-assemblies-god-became-catholic-journey-home-program/
Tim met a Marine who really knew his faith and challenged Tim to study Catholicism from Catholic and historical sources.
Again ... He didn't convert from study of scripture ... he converted by reading RC propaganda ... and the church fathers. Which in and of itself tells me his exegetical skills are nonexistent.