Darth Vader Kuu

You need to be familiar with the eligibility requirements for naturalisation which are basic and non-ambiguous: good moral character, continuous residency in the statutory period, physical presence, age of majority and not already a US citizen by virtue of citizenship of a parent. It's that simple and has nothing to do with your employment history, your trips abroad (provided they do not contradict the previously stated eligibility requirements) or the baseless musings of a random official at an airport.
Once you understand these fairly straightforward things, you will realise that this airport officer you spoke of did not make a "good point." To avoid doubt, why do you believe that the airport officer, in giving his opinion, made a good point?

Replying to ext:
1) You do not have a big problem. If everything you've described above is correct, and there are no potential barriers in your application or immigration history such as crimes of moral turpitude, than it would seem that you have so far established eligibility to naturalise as a United States citizen
2) The immigration officer at your last port of entry does not have authority to decide your naturalisation eligibility and probably is not even familiar enough with the eligibility standards and how they are applied to arrive at such a bold and misleading conclusion
3) Even if you did have trips lasting over six months (which you should always avoid as much as possible since your residency is in this country), documentation of legitimate reasons (schooling, working abroad with a US company, visiting/caring for non-US resident relatives, etcetera) are accepted as long as you continue to satisfy other aspects of the physical presence and continuous residence requirements
4) Google "USCIS + 913 + physical presence" and read the first three paragraphs of the USCIS link that comes up. Once you have read it, you will see indeed that you do not have a "big problem."
Good luck!

I never said accummulating less than 30 months of physical presence in the United States during the statutory period could be surmounted when eventually applying for naturalisation. As long as you are applying based on US residency of five years, you clearly need to accummulate at least 50% of those five years (30 months or a minimum of 913 days) physically present in the United States; if you have not accummulated at least 50% of that time yet then you need to delay your naturalisation application till you do.

Replying to ext:
1) You do not have a big problem. If everything you've described above is correct, and there are no potential barriers in your application or immigration history such as crimes of moral turpitude, than it would seem that you have so far established eligibility to naturalise as a United States citizen
2) The immigration officer at your last port of entry does not have authority to decide your naturalisation eligibility and probably is not even familiar enough with the eligibility standards and how they are applied to arrive at such a bold and misleading conclusion
3) Even if you did have trips lasting over six months (which you should always avoid as much as possible since your residency is in this country), documentation of legitimate reasons (schooling, working abroad with a US company, visiting/caring for non-US resident relatives, etcetera) are accepted as long as you continue to satisfy other aspects of the physical presence and continuous residence requirements
4) Google "USCIS + 913 + physical presence" and read the first three paragraphs of the USCIS link that comes up. Once you have read it, you will see indeed that you do not have a "big problem."
Good luck!

Just to add to what others have already said, if you want to travel abroad, you must use a US passport. You should not exit or enter the US on a foreign passport if you are a US citizen.
From the State Department Website:
"Most U.S. nationals, including dual nationals, must use a U.S. passport to enter and leave the United States."
http://travel.state.gov/content/travel/english/legal-considerations/us-citizenship-laws-policies/citizenship-and-dual-nationality/dual-nationality.html
Once you're abroad, though, you are free to use your other passport.
If you have no intention of ever traveling abroad, then you don't need to get a passport, but it is good to have: it's easier and cheaper to replace than a naturalization certificate and it counts as proof of citizenship.

I agree with you, the only reason I signed up for selective services is because I had to apply for FAFSA. If not, I would've not done it out of ignorance.

Just my 2 cents.
I've been living in the US for almost 20 years, my son grew up here (wasn't born here though) - and we have never even heard of selective services before he graduated from high school and applied for FAFSA. That's when we've got a letter in the mail stating he had to register - otherwise no money for college. So he did.
I don't find it weird or not-believable that OP forgot/didn't know about SS registration.
However, (sorry, can't find an English equivalent): незнание закона не освобождает от ответственности. Chances his appeal will be granted are slim.