"Then you will know ..." Then? After what? How is this truth known?
It is known after obeying all that Jesus commended. Therfore, the truth that is thus acquired can only be truth of the sort that is acquired in such a way. You will not thusly learn molecular chemistry, for instance, and therefore molecular chemistry is not the sort of truth that will set you free — at least so far as the meaning of this biblical citation.
God's will is free. That musch is true. Beyond that (as far as what Rich said) is speculation, and what the apostle Paul called "running beyond," something he was very earnest to not do. It it would have been a bad idea for Paul to do, it is an even worse idea for Rich to do.