Where the estate of a decedent is allowed an estate tax charitable deduction under the provisions of section 2055(b)(2) (with respect to property over which the decedent's surviving spouse was given a power of appointment exercisable in favor of charitable organizations) subject to the later disallowance of the deduction if all conditions set forth in section 2055(b)(2) are not complied with, the running of the period of limitation for assessment or collection of any estate tax imposed on the decedent's estate is suspended until 30 days after the expiration of the period for assessment or collection of the estate tax imposed on the estate of the decedent's surviving spouse.