There's a clash between the politics. Chinese politics do not tolerate Democracy and separatist activities while Western politics said China should therefore they are violating human rights. This is against China's constitution.
This is nothing about religious freedom. Tibetan Buddhism is welcome but there's a fine line if you cross it to a political side, the Chinese may become abusive and radical which the Western don't like. Bejing do have a Tibetan Buddhism temple while Tibet has 4-5.
Dalai Lama for the Chinese is political figure therefore if they find any monks carrying his picture, they have broken the trust of the same political ideals as the Chinese.
