This is pathetic indeed from Monbiot - but no longer as unexpected.
Outside fascistic circles, who disagrees that anyone is entitled to debate the facts about anything?
Note how Monbiot hides behind official truth in the case of Srebrenica. No need to expose exactly what Ed Herman said that was false or refute any argument made that was illogical. That would take effort. Easier to just assume that anyone who questions the official story is an irrational - and presumably immoral - denialist.
Note, however, how the numbers of Iraqis killed in the war, or the numbers of indigenous peoples killed by European colonialism is VERY questionable. There exists no official number in these cases that no one is supposed to dare question. In these cases anything goes. Go ahead and debate.
If Monbiot want to ASSUME the official story about Srebrenica (or Rwanda) is accurate then that - of course - is his right. He may even be correct. However, without seriously engaging with Herman's arguments, disparaging him the way he does is inexcusable. Its cowardly. Smearing people (like Medialens) who merely defend Herman's right to question the official story is even worse.
Herman may be wrong (I'm not at all sure - especially about Srebrenica). The issue isn't just how many people died but HOW they died in about a two week period when there was major combat going on between different sides. When you also consider that people like former US Republican senator Bob Dole have run the ICMP (which Monbiot cites as if it were a neutral scientific body) then there is certainly a rational basis for doubt. There is no rational basis for a knee jerk disparagement of a writer like Ed Herman.
We can't study everything in detail, and we all forced to make certain assumptions. However, what Herman is suggesting - that the West has inflated particular massacres - is hardly a far fetched notion without historical precedent.