Questions on possible inherited 401k

Sorry this is long but I want to be thorough. In tn, divorced my ex last year and he drank himself to death earlier this year. He had no will and has one adult son (we had none together). I found out I was beneficiary on his 401k. Filled out all the claim paperwork and the people I talked to at his 401k company, Empower, were super nice and said they would be in touch to set up an account for me. That was about a month ago. Fast forward to Monday morning and I get a call from a company, Definiti, that said they were the plan administrator and wanted to let me know his plan automatically revokes spouses as beneficiary upon divorce. Ok. That's fine, I thought I had been removed anyway. I asked for a copy of that policy statement thinking my stepson might need it when he claims. She said she didn't have it but since I was revoked I had no legal right to a copy but she took my email address in case she could find something to send.

I'm even more confused now. I did receive an email from Definiti, with one sheet that has a highlighted statement under Payment under participants death:
[ X ] A beneficiary designation to a spouse shall be automatically revoked upon the legal divorce of the Participant and the spouse. To me, that means I was removed which is fair and what I thought he would have done anyway. His employer is the one who provided me the contact information for Empower and said I would have to call them to process the claim; they never mentioned Definiti. In the email from Definiti they said I would have to call Empower to find out if his son could claim the account as the estate executor/next of kin. Well if Definiti is telling me I can't claim it, shouldn't they be able to tell me if he can or cannot?

I called Empower back to ask if his son fills out the same form I did to claim the account or if it's a different one since he was appointed executor and next of kin. The rep I spoke with said he didn't understand what I was asking because I am the sole named beneficiary and no contingents were named. I told him about the call from Definiti and he said he didn't know anything about that because as of June 8th, they had confirmed I was the sole named beneficiary. I asked him who Definiti is to this process and he said he didn't have access to see who the individual plan administrators were so he didn't know. He filed a request for confirmation that I am the named beneficiary and said I should receive something in writing (snail mail in 7-10 days) confirming if I am still the beneficiary.

I have never had to deal with anything like this so I am confused as to why there are 2 companies both claiming to be over the 401k and telling me different things. If the company with the actual account says I am the beneficiary, does the 3rd party plan administrator override that? (No, I'm not trying to be greedy or I would have done that in the divorce settlement. We don't even know how much is in the account. My stepson doesn't want it to go to the estate out of spite because he would have to split it with a half-sibling he just found out about.)

At this point I'm going with I can't claim it and just asking all these questions so I have a better understanding of how this works. I'm now asking more in-depth questions because I have my own 401k and want to make sure my beneficiary doesn't run into issues from hidden clauses. If I were married and name my husband as the beneficiary and after a divorce I still wanted him to be the beneficiary, would a clause like that make it impossible even if I actually did still want him to be the beneficiary? The plan administrator can override who I name as a beneficiary? That doesn't seem right somehow.

I appreciate all the answers. For someone who's had a 401k for 30 years I never realized how tricky and confusing it could be for the survivors when you kick the bucket.