If your intent is to defer taxes as long as possible (which may or may not be the best long term tax strategy), withdrawing from the older spouse's 401(k) an amount equal to the 401(k) contribution of the younger spouse's 401(k) instead of making neither the distribution nor the contribution will mean that RMDs will be lower for the older spouse and higher for the younger spouse when the younger spouse becomes subject to RMDs than they would otherwise be.
