From your post it appears that you wanted to know the reason for rejecting your application. You know the reason now. Presumably this has been told to you by UPSC. In that case what further information you need from UPSC?
RTI helps in getting info only. If you are aggrieved by the info provided you may represent to the higher ups or seek remedy through court of law. Your second part of the query relates to the nature of your experience and whether it will count for consideration. It depends on the requirements specified in the advertisement for application etc.