I assume your hiatus is over?
BFD - not your kid and none of your business
Did you even bother to read the article or did you stop at the headline ?
I don't agree with going "public" with it. Some things are better left in the privacy of a home. There is no need for that, especially at this age. However, I think the parents should let their child explore his own Being as he or she sees fit. If the child eventually grows up and reaches legal age, and wants to transition, that is his or her choice.
Mental issues will come about depending on the type of support that the child receives from parents, family, friends, and the community and/or society at large. Furthermore, the child's own temperamental style and personality (both are distinctly different) will also play a large role in how he or she deals with things. Though, to a great extent, a lot will have to do with how his community, and society at large, treats him. We often underestimate the powerful impact that institutions have in determining our emotional world. We know that Institutional Betrayal has been associated with a whole host of difficulties. Institutions housed within communities and societies can greatly determine this boys emotional world, and how he perceives himself, others, and the world. But that is a "tall order." He will most likely be shunned from certain institutions, which is why it was probably best not to make this a public event.
Its impossible to say whether or not the child will have mental health issues. Granted, there are some variables that have strong predictive power in possibly determining a child's long-term mental health issues, however, it is still impossible to say how he or she will react later on in life.