The author made no reference to anything needing the bible for proof. His contention is that Clavin, Zwingli, Luther said something. One would not look to the bible to discern what these gentlemen said many centuries later. Likewise one does not look to the bible to determine what President says about foreign monetary policy in 2003.
If you read back through the thread you'll see that the issue of biblical proof had to do with the name of the website.
It claims biblical answers for catholic beliefs and the fails to use any scriptural reference for it's claim.