Dividends are governed by Article 10 of the DTA, which generally limits source country taxation to 15%.

Even if Swiss tax was withheld at the wrong rate (e.g. 35%), your client would be expected to file a refund claim for any excess beyond what the treaty provision provides for and not be permitted to include for FTC purposes voluntary taxes paid to or withheld by Switzerland.

HTKO requires grouping of passive income before a determination is made.  You cannot arbitrarily KO income that should be in the passive basket and move it to G/L.