The objection is that if an act occurs despite an infallible divine report of its nonoccurrence, the report would become false; that is impossible. Must the act therefore be intrinsically impossible?
The argument requires distinguishing the assumed act, its consequences, and the entire set of circumstances. If a contradiction follows under an additional condition, it matters whether the problem arises from the act’s essence or from combining its occurrence with an infallible contrary report.
The contradiction belongs to the combination of claims, not necessarily to the bare description of the act considered on its own.