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Wouldn't it just be written off as a conspiracy theory that provides little to no evidence for its claims?
If the only thing that gets this on HN is Seymour Hersh's reputation (which has lately become somewhat questionable) then you might want to reconsider. Plus, the quality of the comments has not been very good so far.
This is an actual case of speaking truth to power. He clearly (and rightfully IMO) does not trust the US government and his "somewhat questionable" and recent work has continued that trend. Is it any surprise that the same institutions/people that continuously carry water for the government now rush to label him a conspiracy theorist?
No level of reputation or historical track record should exempt anyone from the basic responsibility of providing evidence for claims they make.
However, evidence is not the only valid form of claim-making. Predictive power also has value: if someone can assert something unlikely without evidence, but with sufficient specificity that it describes a subsequent development very accurately, then it's fair to presume that person probably has insight into the issue.
So while I am somewhat skeptical of Hersh's claims, they're also detailed enough that corroboration could be sought for.