I don't know WHAT to say on this one.
I can't say it's unethical/immoral (like men trying to give birth), because if this article is true the men are producing the milk through natural means. It's particularly interesting the story of the Sri Lankan man who 'breastfed' his kid because the wife died.
Still, nature gave women breasts and the ability to easily produce milk after childbirth. Even if men can produce it, I don't think they should unless it's because of dire circumstances like the case of the Sri Lankan man.