I haven't seen the whole letter you have received so I can't comment much. However, if the main reason for denial is "employer can file LC for you", you shoulde DEFINITYELY appeal because CSC is not playing by the rules.
As you know, in order to get NIW approved, you need to show that a waiver of LC is in the national interest, and need to pass a 3-prong test. I guess that you passed the first two (i.e., you work is of intrinsic merit, and of national scope). The third test is "it is contrary to national interest by depriving the prospective employer of the service of the alien by making the position available to U.S. workers"
Therefore, as long as you have provided sufficient evidence to show that it is contrary to the national interest by depriving the prospective employer of the service of the alien by making the position available to U.S. workders, you qualify for NIW.
Whether your employer can or can not, will or will not file a LC for you is irrelevant to your qualificatoin. And it certainly should not form the basis of a denial.
Also, notice the word "prospective employer". "Prospective employer" is not the same as your current employer which sponsored your H1B. A prospective employer could be any company or organization that needs someone with your expertise in the present or in near future. It could be a company that your have never heard of, or never contacted yet. How could the USCIS know whether these prospective employers can or cannot, will or will not file LC for you? Therefore, even if your current company can get you a LC quickly (and by doing so avoid harming the national interest), you can still pass the third test. This test should be applied to a hypothetical "prospective employer", not to one particular company that has sponsored your H1B. I think you need to hire a good lawyer to prepare a good appeal.
Finally, good luck to you. Remember, never quit, never surrender, fight every inch, fight to the end, fight until you win. And let the folks at USCIS know that it is absolutely easy to approve. But to deny a case, they need to spend much time and effort.