Validity: The passage explicitly states that Bøhn argues trinitarian self-consistency problems vanish "when one realizes that the Trinity is just an ordinary case of one-many identity," and he draws on Frege's concept-relative number-properties to support this, making both the argument structure and its presence in the passage clear.
Confidence: The argument is clearly stated: Bøhn uses Frege's concept-relative number properties to support the claim that the Trinity is an ordinary case of one-many identity, which in turn resolves self-consistency problems.