It's a shame that they have not gone down the path of forming a breeding troop. Australia's public zoos are shockingly lacking in smaller primates and this is a big missed opportunity.
It’s interesting you mention this as many of us assumed the male transferred to Melbourne with Charlie was Adelaide’s breeding male, who is now represented through offspring at Adelaide. This would have given Melbourne an unrelated pair.
I hope Black and white colobus are in Melbourne’s long term plan, but presumably the intention here is to cater to the welfare of their lone female and give them an exhibit for the next decade while more pressing issues within their collection are addressed.