It depends what you mean by "exorbitantly priced." According to Form 8962 instructions, "the coverage offered by your employer is generally considered affordable for you and the members of your tax family allowed to enroll in the coverage if your share of the annual cost for self-only coverage, which is sometimes referred to as the “employee required contribution,” is not more than 9.83% of your household income."
In other words, if your wife's self-only coverage would have cost more than 9.83% of the total household income, then it would not be considered affordable and she would qualify for premium tax credits.
You probably won't be able to exclude your wife using this rule, but you can do the math yourself to figure out if you qualify. If she does not qualify, your child would still be eligible for marketplace coverage, but you would have to calculate Column B, the second lowest cost silver plan, as if he were the only member of the family. Presumably, the amount reported on your 1095-A includes only your wife and son in column B.
If your wife does not qualify for the exemption, you can try to contact Covered CA to issue a corrected 1095-A that would have the correct Column B amounts. They might just tell you to calculate it yourself. I could not find a calculator on the California website, and the federal calculator does not include California since they operate their own marketplace. But you can get an idea of what the SLCSP would be without your wife, and chances are once you use that number it would result in you not receiving any premium tax credit.
