In general .—
Except as may be otherwise provided by regulations, a trust forming part of a defined contribution plan shall not be treated as failing to constitute a qualified trust under this section solely by reason of allowing—
(i)#
qualified distributions of a lifetime income investment, or
(ii)#
distributions of a lifetime income investment in the form of a qualified plan distribution annuity contract,
on or after the date that is 90 days prior to the date on which such lifetime income investment is no longer authorized to be held as an investment option under the plan.