333.13. Sections 333.9 to 333.11 do not apply in respect of a taxpayer’s grant of a restrictive covenant if one of the results of not applying section 421 to the consideration received or receivable in respect of the restrictive covenant would be that paragraph a of section 28 would not apply to consideration that would, but for sections 333.5 to 333.16, be included in computing a taxpayer’s income from a source that is an office or employment or a business or property.