As per DOPT directives, postal order must be accepted through out India by all Public Information officers. Search website of other State authorities and specifically Gujarat Information Commission.
For simple things, let us not waste time to convince idiots and focus on information and pay challan first to get information. You have still the right to file a complaint later if you deem that it relieves some other applicants like you in the future from such irresponsible demands of PIOs like him. For filing complaint you have to search SIC rules in Gujarat on mode of payment of RTI and enclose such verbatim section in such rules and regulations.