My comment:
(a) True, Reuters does not say where Norbu Dunzhub makes the remark (Beijing or Tibet)-- and what the occasion is.
(b) It is possible that Norbu Dunzhub makes the remark in Beijing--specifically 国新办举行民族区域自治制度在西藏的成功实践发布会. See the headline banner in 国务院新闻办公室's home page.
However, neither the Xinhua report nor the 白皮书 itself (released on Sept 6, 2015; titled: 民族区域自治制度在西藏的成功实践") http://www.scio.gov.cn/zxbd/tt/jd/Document/1446894/1446894.htm
mention 班禅喇嘛 at all; I read both twice.
(c) The last time China released a Tibet white paper was Apr 15, 2015.