So he started the turn OK and then lost it in the turn? or lost it as he rolled into the turn? which is it? Either way trying to turn IMC and descend when instead you can climb with wings level is a very poor choice.
Either one---my point being 4 or 5 posts ago was that this statement may not be true: "having already decided it wasn't a better idea to turn around". I believe he made the decision to turn around, albeit too late. I believe the initiation of the turn was deliberate, where he "lost it" after that is irrelevant.