Have read the OP but not the whole thread so excuse me if this has been said or the thread's moved on!
From an ex-wife point of view, I would say be wary of assuming that you have the full story.
From my ex-h's point of view our 15 year old daughter is socially isolated, moody, non-communicative and evasive when he tries to call/text/Skype her. He tells other relatives that he thinks she's depressed and needs help and that I'm in denial about it. He also implies that I'm in some way encouraging her isolation.
From my point of view, she is a happy teenager who has her own interests, is happy with her own company, doesn't feel the need to be out with her friends every day after school but has a healthy social life and a small group of close friends.
She does avoid speaking to him. Not because she's socially inept or depressed but because all he wants to talk about is how she's doing at school and check how many times she's met up with her friends that week.
I've explained this to him and tried to get him to engage with her in different ways and find out what she's really interested in. But it's all on his terms and he has a set view of how a teenaged girl should be (a female version of him at 15 apparently) and because she's not then he assumes something must be wrong.
Also I was a horse and dog obsessed Goth as a teen and people thought I was all kinds of freaky too. Well I was, but I was also perfectly fine 
I'm not dismissing your concerns and it's lovely that you're concerned. You could well be 100% right in which case your husband needs to get his act together and tackle his ex-wife about it. I'm just saying it might not be all it seems and the only one who knows the full story is his daughter so maybe the way forward is for him to have a chat with her. No preconceived ideas, just let her tell him what's what. Hope it all works out>