"First of all, how is it logical to register, without objection, to something that you later intend to object to."
It's perfectly logical. You don't seem to have thought this through at all. For the initial Selective Service registration, everyone registers. It's quick and easy. If and when a draft occurs, then objections can be lodged, but, of course, not everyone is going to be "called up" so to speak. If CO's made their objections ab initio, Selective Service would have a bunch of cases to deal with, a lot of paperwork, and some hearings to schedule. This would be burdensome. Instead, by moving objections to when an actual draft occurs, Selective Service reduces the administrative costs, because a CO's case need be dealt with only if that person has been drafted. Instead of dealing with every potential CO, the system deals only with those who've actually been selected. Given that we currently have no draft, that means we have to deal with 0 objections. What you think is logical is having to deal with countless objections that, because we have no draft, will likely be irrelevant.
"It's akin to signing a contract and later objecting to the provisions of the contract."
No, it is not.
"The very fact that you refer to the SSS website for guidance on the issue argues my point"
No, it does not.
"once you sign up, you are subject to *their* rules and their whims"
You are subject to their rules because those rules are the law. You are subject to them in the same way you are subject to IRS regulations, to the federal criminal statutes, and so on. Failure to register does not absolve a person of the requirement to obey the law. The only way to avoid the operation of US law is to travel beyond its jurisdictional reach.
As far as "whims":
http://biotech.law.lsu.edu/Courses/study_aids/adlaw/706.htm
"To the extent necessary to decision and when presented, the reviewing court shall decide all relevant questions of law, interpret constitutional and statutory provisions, and determine the meaning or applicability of the terms of an agency action. The reviewing court shall...(2) hold unlawful and set aside agency action, findings, and conclusions found to be...(A) arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law"
You're arguing law with an attorney, just fyi.