Two points under the cutoff on the RIAS and five under on the KBIT are something worth arguing about. Both tests are of the quick-assessment variety, taking 20 minutes or so to administer, with really low discontinue thresholds that can cause a child to be underestimated. If a child misses two consecutive questions on a section, that can be the end of that section.
I like epoh's suggestion of asking for the GT program on a trial basis, citing the test scores and their tendency to err on the low side.
I'd also suggest that you talk to them about testing him with a more comprehensive test like the WISC-IV... or if they won't do that, take him to a private psychologist for that kind of testing. There are two potentially useful takeaways from this exercise... you may come back with a higher score on a more accurate assessment, which you can use to champion for him at the school for more interventions. You may also uncover a weakness that you could help him address, setting him up for success on a gifted screening next year.
