This treats public funding as already decided and attaches a new demand to it. A principle that tells you what should happen once campaigns are publicly funded gives no reason to start funding them publicly, which is the conclusion we're trying to reach.

This applies to a situation the advocate never talks about. (C) is about a single race where one candidate is collecting most of the big money. In that case, (C) says public funds should go to that candidate's rivals. The advocate isn't talking about lopsided races. The proposal is to subsidize campaigns across the board. The advocate's worry about large contributors is different too. The worry is that officials end up serving those contributors after the election, not that one candidate raises more than another.

This works against the advocate, if it applies at all. (D) says that when public funding helps the public but also gives a special benefit to certain individuals, those individuals should pay part of the cost themselves. In other words, don't fund the activity entirely with public money. That is a limit on public funding, not a reason to provide public funding.

This only tells us who should be denied subsidies. A rule about who is ineligible for a program assumes the program exists; it gives no reason to create a subsidy program, and creating one is what the advocate is arguing for. Also, nothing in the stimulus mentions anyone who would not have run for office without subsidies, so the principle in (E) would never trigger.