I won't bother restating most of what has been said by people above, but I will add just a bit more to the discusion. With your friends size, MT has some definate advantages in applying his reach and, by his weight once in good shape, power. MT also has a very "hands on" approach to training, you train it like you would use it. This is a real advantage if your friend is looking for a slef-defense type art. While traditional arts work great in real confrontations, the level of dedication and training to really understand and apply those arts is very high, and something not too many people are willing to put into their training.
If your friend is looking to compete BJJ is what he should look into. The entry cost is low for gear, the copetition levels are variable by desire of the competitor and the areas with copetitions are spreading constantly it seems like. The style offers solid ground work with a varity of technique. Yes, early BJJ success in UFCs was over blow. In a tournament organized by the Gracie family, with a rules set they were already used to competing under, the results were as they should have been. Lately the family has taken some loses because the level of competitor they face is higher than it was in the early UFC days.
If 90% of fights end up on the ground it is only because 90%+ of people in fights don't know how to fight. And, throwing in my rather worthless{research wise} personal experience, all but one of the fights I've seen have staid up and doen damage. Going to the ground, close grappling is the reaction of many people because they think its safer, harder to get punched/hurt in a grapple. My pointless point for the day.
The Hung Gar I would recomend if your friend is looking into a long term style. It will be something that, because of its depth, he can train in for a life time and not get to a point where all he has left are a few competitors skills and an old man's body. Plus if you train in the same style, you can push and inspire each other, pull each other through the low points where you really don't feel like training etc. Of course, if he trains in a different style, you can share what you learn and broaden the knowledge base you are working from.
Always enjoy what your doing, support each other and train hard for the right reasons.
Kail