Like most people have said, some Buddhists eat meat. Like Christianity, there is
more than one sect of Buddhism. As it spread out of India (or Nepal, I guess), the
missionary monks changed the religion to be more acceptable to society. For example, in China, the tradition of monks/nuns going door to door begging for food (which is what the Buddha himself did) stopped. It was seen as bad and parasitic, not part of the historical culture like in India. Only at this point did the idea of clergy being vegetarian catch on. When they beg for food, monks are to eat whatever they are given. In China, where they shop for and cook their own food, they're usually vegan.
Anyways, Tibetans are often considered as kind of the crazy black sheep of Buddhism.
They often follow a secret tradition, and they include a strong guru culture, with
blind obedience to the point of morbid masochism encouraged. The Dalai Lama is a political figure, like the Pope. Some have been nasty people. This one is pretty nice - they got lucky. He puts a good spin on things PR
I guess what I'm saying is that we really shouldn't expect too much from him. It was almost plain dumb luck for the Tibetan Buddhists that he's regarded as such a nice guy in other respects. He's certainly not perfect.
Still ... it would be nice if he were vegan. He should be, of course, if he wants to
promote non-violenece. But people don't always practice what they preach.