> By that reasoning, a presidential candidate of Chinese descent who was a natural born American citizen but had relatives back in china would be disqualified
Not so. The Constitution is very clear on eligibility requirements for the President. A natural born American citizen of Chinese descent who otherwise satisfies the requirements in Article II, Section 1, Clause 5 is perfectly eligible to run for the office. If there is concern about potential leverage foreign states have over that candidate--as there rightly would be if our natural born American had close family in PRC--voters might vote for someone else. My position is that such a motivation on the part of the voters is ethical.
> I accept that I do not qualify for a high security clearance because I’m married to a Chinese national. I don’t think that should have any bearing on any other jobs that don’t require such clearances (nor my wife nor my son should be subject to such restrictions).
First, I agree that your or your son's relationship to a Chinese national should not be sufficient grounds to deny you or your son any given job. My position is that a narrowly tailored policy to reject candidates with high risk of coercion from sensitive positions, or to limit such employees' access to sensitive data, is probably OK. Having close family residing in PRC unfortunately does raise the risk of coercive pressure being applied. If your wife has no surviving close relatives in PRC and she never goes to visit, you and your son should be assessed to have no greater vulnerability to coercion than any other citizen with otherwise similar circumstances (debts, addictions, etc.).
Second, I am curious why you disagree completely, yet accept that your relationship with your wife may disqualify you from holding a government security clearance. That means you accept that the government has an interest in protecting classified information from foreign powers, and that your relationship raises your risk profile. Do you not accept that private companies have an interest in protecting their IP and customer data from theft or sabotage? Or do you not accept that your relationship also raises your risk profile for these positions? Just because a position may not require a clearance does not mean that position is not highly sensitive to a potential insider threat. And unfortunately the PLA's targets are not restricted to intelligence agencies; they target virtually every sector of our economy.