Optech would apply the interest earned on the FRNs to the interest that Mr. Sollberger owed Optech and he would pay the difference, if he felt like it.
The statements listed the FRNs as collateral (although they had already been sold) and showed the quarterly interest purportedly earned on the FRNs (which were shown as a credit against the loan interest).
It seems pretty clear that Mr. Sollbeger was not planning on paying off the loan in seven years and getting his FRNs back, since it would have been disturbing to him that the statements stopped if he had.