I can think of many reasons.
Fear of Barry.. fear for his family If Barry was this controlling, it's hard to say what he has threatened that we haven't seen a text about or hear about. Suzanne was confiding in him for 2 years. He had seen some texts at some point because they switched to a different method of talking after Suzanne told him Barry saw some messages. Then his daughter saw some and they quit talking for a little while. I think fear. Maybe he felt him coming forward to draw attention to him and he knew 100% he wasn't involved. I know I am one to assume LE will figure it out, so maybe he felt it would be easy for LE to figure out what happened. Then the long you wait the harder it might be to come forward. I think the fact he cooperated when he was contacted and didn't try to hide then is a good sign. Protecting Suzanne's girls maybe a physical thing as well.. maybe he feared coming forward would put them in harm if Barry found out and was still free. It's hard to say and of course not ruining his own life would be a huge factor. Doesn't make it right, but it doesn't mean he didn't care for Suzanne and wish things turned out differently.