Deleting them is understandable but could you leave a moderator message that forbids assertions of unverifiable claims? Or even better; make it a rule. And enforce the rule as strictly as Jeff enforces the "no swearing" rule.
Simply whitewashing everything is not a long-term solution. This isn't the first time nor will it be the last time that such disagreements occur. Please address the cause, not the symptoms. What happened to this thread was just a symptom.
The cause, simply put, is the tendency of some members, both pro and anti-China, to proclaim assertions that are unverifiable and portray those assertions as fact. The more sceptical and rationally-minded members then jump in to smash apart the snowballing heap of unverifiable claims. The original claimant, perceiving a slight to himself, then initiates a chain of back-and-forth arguments that derails the thread.
All this could be prevented if the rules clearly disallow portraying conjecture as facts, and any attempts to do so will result in deletion and possible suspension. In other words, make it compulsory to put a disclaimer before posting conjecture.