Nonqualified IRA funds rolled into 401(k) Plan

[401(k)athryn]

I am considering taking over administration for a plan into which one of the doctors rolled his nonqualified IRA balance in a prior year. Is a rollover from nonqualified (not 457) accounts permissible in any 401(k) Plan (or any qualified plan)? I believe the answer is no, in which case, the next question would be - what to do about it? I don't want to recordkeep these assets, so should I just suggest the doctor roll the money back out as soon as possible?

Thanks!

[401king]

Nonqualified, or after-tax?