What exactly is your question? Whether to allow the school to test him? Whether you should be in public school? Just blowing off steam? Something else?
Giftedness questions have not been treated very kindly here. I am sure you have searched for prior topics on it. But this is a financial board, not a childhood development one. So take all opinions here with a grain of salt: there is more spouting off than genuine experience and wisdom, at least around this topic.
Let me take the opportunity as the first response to go down the rabbit hole a bit: the thing about giftedness, if measured as IQ, (which is not always a good measure for really young) is that it is a normal distribution. So if your kid tests as a 130 IQ, (2 standard deviations, or 98% by whatever means you are using) many people will just say "they are really smart. Lucky them, they have it easy!" But it isn't easy. Nobody would downplay the need for support if your child tested at an IQ of 70. But that's just it--those scores are both equally different from "normal," and it's not a matter of simple ability; it also changes how they learn. A highly gifted child can struggle with school just as much as anyone; they might even be able to hide their struggle, but then they won't just fail to reach their potential, but can develop severe mental issues as well. And many highly gifted kids are "twice exceptional," which means they have a mixture of high ability and developmental issues, which need to be addressed together.
So the real point of supporting a gifted child, or finding out if that clinical definition fits your child, is not to maximize their lifetime earnings or prestige, but to understand how to help them develop naturally into who they are. Of course, as in all things in the human condition, this idea is twisted beyond recognition by parents with their own agendas. Those GT tests for kindergarten? There are study books for them. Hell, there are *prep classes* for them. So I don't discount the ugly expression of this topic that you see around you. But you can't control how other people will screw up their kids; you can only control how you approach things, and what you will do. If you think your son may be gifted, the best thing to do is to support him and listen to him.
The #1 place to begin your own research into what this is all about is Hoagies Gifted. They also have links to parent groups in your area, and books for deeper reading.
A little background on my experience. Our son began reading individual words just as he turned 2. (I'm not talking about "at" or "the." I'm talking about "hippopotamus" and "giraffe.") While we worked with him on the alphabet, etc. this was his doing--we discovered it, not caused it. It so happened during the following year we had an opportunity to move to Ireland for work. As we were planning this uprooting of our family, his reading also progressed. Distracted as we were, we didn't really do anything about it, in regards to our move, until about 2 months before D-Day. We started to worry about what kind of development support options would be available for us in Ireland. So we sprang for a WISC III test with a child psychologist, with the goal of targeting his development until "normal" school age. He came out of that test, age 3 yrs, 1 mo, being judged at a 2nd grade reading level, among other measures. The psychologist said, "get him in school."
So since then, now 3 years ago, we have had to advocate for him with his teachers, who are all (deservedly) pretty jaded about every person's "special child." Only, it isn't always bragging, but brings as many needs as it does opportunities. We have spoken with every teacher he has had about his situation, and bring the documentation, too: tests, teacher evaluations, etc. Our school district has just conducted their annual GT testing, and so now he is officially recognized by his school. (One bad thing about a very large, public district--no flexibility to circumstances. Follow the process because It's the process, no matter the situation) We have yet to see what effect this will really have, although extra attention is promised.