If the distribution was made directly from his 401k plan - that would be his responsibility to pay taxes on the distributed amount and early distribution penalty is applicable.
Usually the mechanism of division of the 401(k) account in divorce is through a qualified domestic-relations order (QDRO).
QDRO is a court decree under state law that addresses issues with child support, alimony or marital property rights. When the 401(k) is divided according to QDRO - you, as the alternate payee, may take out 401(k) money without early distribution penalty (even if you are below 59½) , but the distribution will still be your taxable income.
That was your choice to take a distribution - generally your other options are
-- to roll your portion of the 401k into your IRA.
-- split the account into two separate accounts and leave with the same administrator.
Let me know if you need any help.