It is strange reading modern Scholastics arguing that money is capital, because the arguments seem to be so facile. They overlook in so many ways the truth of the situations that it is somewhat stunning. To say that money has become as a seed because if judicially planted it will bear fruit is simply absurd. Given the right conditions a seed will grow from an intrinsic principle, but there is no such principle in money. The fruitfulness that comes from money arises from the fruitfulness of the thing it is exchanged for. However, this fruitfulness is not intrinsic to money and therefore money itself is not capital and not fruitful. This is manifest from the fact that money as money can be used to buy things that are unproductive (such as bread, wine, etc.) or destructive (the labor of an arsonist).
However, seed as seed is productive because when it is used as seed it will produce fruit. Money as money will not produce anything and the claim of its productivity is based solely on what it is exchanged for, which may or may not be productivity. This is not a matter of failure of judicious planting, but based on the nature of money itself.