I’m not sure I understand your wording here. ‘Intersex’ is a term referring to a number of genetic conditions that don’t really conform to your explanations here. Firstly, describing the conditions as deriving from damaged genes can certainly be argued. If we’re talking about SRY fragments being separated from the Y chromosome then sure, that’s gene damage. Much of the rest of the conditions result from in-vitro fusion of zygotes, so fully intact sets of chromosomes in the zygote, just not the normal complement. In the case of a chimeric individual, you essentially have what should have been fraternal twins combined into a single zygote. But this may be mere semantics.
The real problem with your statements here is the claim that intersex persons are 1 sex with different physical characteristics. An individual’s phenotype is derived from their genotype, it can’t develop without the genotype to code for it, so the physical traits match the chromosomes. You seem here to suggest that the physical traits are some aberration that don’t match the DNA, when it was the DNA that created them. The DNA may indeed be aberrant, but it’s not detached from the physical characteristics.
You say that early DNA testing can be done so the child can be raised according to the DNA present, but what would that mean? What would you do with a chimeric child showing 46XX/46XY chromosomes? The child will likely have both sexual organs, and yes one of them will end up non-functional so past that point parents can simply choose the sex of whichever organs are functional, but prior to puberty there’s no way of knowing which it will be as far as I know.
What would you do about SRY mutations? With Swyer syndrome you have a child who may present 100% female with functioning (albeit not reproductively so) sex organs, who upon genetic testing is found to have a 46XY karyotype with a missing SRY gene? Early genetic testing would’ve shown this child to be chromosomally male, yet phenotypically female in every way. Should the child be raised male? Alternatively you have a phenotypically male child who is found to be 46XX who has an SRY gene fragment from pappa. In either of these cases, owing to the presence or absence of the SRY gene, the children will have the phenotype opposite what their chromosomes say they should have. Yet it would clearly be a mistake to raise them in accordance with their chromosomes, because literally nothing about them will coincide with it.
I don’t think these issues should be confused with transgenderism, which in my opinion is psychological in origin, and while I don’t think such delusions should catered to, especially not with children, I don’t think we should mistreat the biological data regarding intersex persons.