A transfer to even a grantor trust is a change in ownership, with the possible exception of a transfer to a trust of which the grantor is the sole trustee. Even then, how is the employer to know if the participant ceases to be the sole trustee? Although the beneficial interest does not change, title does change. I have no doubt that having the right to change ownership of the NQDC benefits will trigger 451 constructive receipt. Assignment would also violate 409A, because it would constitute a change of ownership by the plan participant before the date permitted by the plan and section 409A.
There is no need for the participant to transfer ownership of the benefits. The NQDC program undoubtedly has beneficiary provisions. The participant can designate the trustees of his trust as beneficiary, thus ensuring consolidation of the NQDC benefits with his other assets and avoiding probate at his death. Treat the NQDC plan as you would treat an IRA, which would never be transferred to a trust.