I think it is ridiculous. Amy has never stopped Ste from seeing the kids as long as he was in a stable situation to do so. They have moved into the village not just because of Ryan's job, but so they can be near Ste. Now all of a sudden Ste wants legal rights and he has nothing on his side.
He doesn't live in his own home, he moves from his sisters house to which ever guy he is currently dating. So where would the kids stay? He has been unemployed for a while and has just started a business with friends money that may fail, he is extremely violent, he is a drug addict who keeps relapsing despite both his sisters paying for treatment and now Tony has. He was homeless and took his kids to live in a shed, he is thief (and took his children along once) and will repeat that behaviour in the future if he needs to. Leah doesn't want to see him and shouldn't be forced to, Ste needs to change his life so Leah wants to see him.
Then there is Ryan and Amy, seems like a solid couple, Ryan is a cop, I am assuming Amy has a job and they seem like a secure enough family to look after 2 kids.
So how can Ste exactly win this? Surely it will only be what Amy allows or no more access than he gets normally..