Ive never been able to understand how Buddhists are seen as a threat to the Chinese gvt?
Buddhists aren't, per se. It's cultural. The Han (Mandarin) race views Tibetan Buddhism as a foreign cultural contaminant to traditional Chinese values. Tibetan Buddhism was once very popular in China itself, primarly because of it being preferred over Chinese Buddhism by the Mongols.
That and anything intrinsically Tibetan stands in the way of the Han culture's absurd claim that Tibet itself is naturally and absolutely part of China. It is a case of China looking back to the Mongol Empire and pretending to inherit all of it...never mind that they spoke a different language, were racially different, all of that. Politics does not have to make sense, only to swell pride and fill the purse.
From my point of view, China's natural borders are those they erected themselves, you know, the only man-made object viewable with the naked eye from space. Let the Han close ranks behind those and everybody will get along fine.
Seriously though...it's not just a Chinese mental abberation. Look upon every nation that rose to significant political and economic power. The first thing they generally did was look backwards in time to some point when a single empire spanned all of what they now have...and then some...and claim that as the true and natural size of their nation. They use that as the argument for conquering neighbors. Look at how many tyrants went forth with armies claiming to be the true inheritors of Rome's glory. The Chinese are doing similar now. That's all.
We should repudiate China, by all means. But at the same time we have to repudiate our own varied cultural pasts. It is all the same sort of grandiose delusion, then and now. Some might suggest that the USA does differently. Or is it perhaps that we claim the once mighty British Empire? Or the world? Some nations don't need an excuse. They don't require a Rome in their past if they can be Rome, or Mongols, or whatever. Modern politics, however, seems to require an excuse, at least for some. That way you can at least pretend that aggression is justified historically. Without that, you have to convince yourself that you are doing for their own good. Or, both at once?