This story brings out the Libra in me, as I see all sides having a valid point.
It seems like the authorities recognise that this couple have a genuine relationship. When criminals can stay here because returning to their country of birth and breaking family ties in the UK would violate their human rights, why can't an exception be made for this couple? It looks like their visa application would be approved, so why not let them do it from here?
On the other hand...she is lucky they are not in the US trying to do this for her husband. I have a friend whose daughter married a Mexican citizen who stayed in the country after his student visa expired. The authorities caught him after the marriage, and deported him. They have to wait 10 YEARS before they can apply for his spouse visa, as a consequence of his actions. At least the UK couple don't have that kind punishment hanging over their heads. And as others have mentioned, there are rules and really, the UK rules are not that onerous compared to the US to bring in a spouse.
My heart goes out to them on the loss of their daughter. I hope they get this resolved quickly.