Posting for traffic no add button

[Autumnchills415]

Hello. An Ex of mine blocked me 5 months ago and it was pretty stressful because he owes me alot of money. Last night he suddenly unblocked me and it was a shock but he hasn't made contact. He has started making posts public and his last post he was saying he's struggling with his head and needs a plan. I told my best friend who showed me her screen and she can add him as a friend but there's no option for me to do that.

Am I wrong in thinking he's set it so I can't add him? Or is that not a thing. I'm not going to react but unsure of this strange behaviour from him. How does Facebook work?