It doesn’t. However, within the political structure of the show (such as it is) the study is presented as a sort of wedge. Bartlett appears to view it as a slippery slope in terms of his administrations politics and fears that it will set a dangerous precedent to agree to purchase a vote in this manner. The “separation” has been a key sandbag for this administration.
Note that the right wing senator was presented as ultra-smarmy and certainly aware that he could get this money somewhere else. It was a power play and an attempt to shape policy in the eyes of most of the senior staff.
I don’t necessarily agree, but it does fit in with the holier than thou we know what’s right passion with which this staff seems to approach their duties. Pragmatically it doesn’t make much sense but it is an internally consistent move.