The emancipation statement is specifically for the rule to pass the exemption to the non-custodial parent, not a general rule for dependency. A parent doesn't lose the "Qualifying Child" just because they got a divorce.
For example, Publication 501 (emphasis mine):
Example 5—child emancipated in May.
When your son turned age 18 in May 2020, he became emancipated under the law of the state where he lives. As a result, he isn't considered in the custody of his parents for more than half of the year. The special rule for children of divorced or separated parents doesn't apply.
