Rate of return; financial involvement with nonutility or unregulated companies. In determining a reasonable rate of return upon investment for any public utility in any proceeding to establish rates or charges, the Commission shall not include any (i) incremental risk, (ii) increased cost of capital, or (iii) after May 31, 2003, revenue or expense attributed to telephone directory operations, which is the direct or indirect result of the public utility’s affiliation with unregulated or nonutility companies.