There is a difference between viatical settlements (where the insured has a terminal condition and chooses to sell the policy) and life settlements. The organization whose members engage in this practice is called the Life Insurance Settlement Association
LISA.
I see no problems if an executive who has an insurance policy provided through the qualified plan takes a distribution and does not choose to receive the policy as an asset. The plan may then choose to retain the policy until the executive dies, surrender the policy or sell it to a life settlement fund without concerns with ERISA.
The insurable interest requirement is apparently satisfied with respect to executives, but not for rank and file employees. The trustee, therefore, upon the retirement or severance of a non-executive, should cancel or surrender the policy. (See the WalMart from about 4 years ago.)
Several questions arise if a qualified plan decides to purchase such contracts. Is the investment prudent? Are there legal risks as well as economic? Does paying for the right give the plan an insurable interest? Is the investment sufficiently liquid if the insured lives another 40 years?
There are life settlement funds which are registered as securities and operate like mutual funds, i.e., provide liquidity. However, the groups that purchase the policies and bundle them together into such a fund usually take most of the profit out of the transaction, leaving the investor with another mediocre investment.