My ex did something similar. After a year of basically no contact- he didn't have a phone!- he decided that he needed 50/50 shared custody of our son. We live 1000 miles apart.
He had also just recently married his new enabler/soul mate. This is actually discussed in Lundy Bancroft's Why Does He Do That?, how the abuser ropes in new prey with sob stories of the wicked ex who keeps him from having a relationship with his spawn.
It's also a convenient excuse for all of his bad behavior with her. He wouldn't drink so much/get so angry if only evil ex wasn't keeping the kids from him. It's all someone else's fault, and keeping the new enabler triangulated with the evil ex is a great distraction from the reality that they just married an abusive alcoholic.
This is temporary. He might try to push it pretty far, but it will end. It's nothing to do with actually wanting more parental responsibility or quality time with the kids. It's about winding everyone up to keep the focus off his drinking.