You're probably correct that it's the language barrier. The message has very little to do with the messenger, and I can't see who's claimed otherwise.
The difference seems to be about whether we SHOULD discuss the messenger. Assange still has the power to decide what to publish, and maybe more importantly when to publish it. Everyone who has a message to convey will wait for the right time to do so. This is true for political statements, for press releases, for when you ask your girlfriend to marry you or for when you tell your parents that you failed an exam. It would be silly not to accept that Assange cares about timing.
A discussion about the messenger shouldn't be seen as a dicussion about the truthfulness of the message. For example: The Russian government accused the Ukrainian government of being fascists, and one of their excuses for entering Crimea was that they needed to protect the Crimean Tatars from these fascists. But the Tatars are pro-Ukrainian, and many of them fled when the Russians took control. Those who remained are being harassed, and there are Tatars who were even denied re-entry to Crimea after having traveled to Ukraine. Sure, there are far-right extremists in Ukraine. Of course there are. But the Russians didn't want to admit that the phenomenon is far more prevalent in Russia. Knowledge of the messenger helps us to put all of this into a context.
All I'm saying is that we should be generous enough not to censor discussions just because we're not interested in them. In this case, it means discussions about both the message and the messenger. When combined, the outcomes will provide us with even more information. Ad hominem arguments like "you're obsessed with the messenger" are designed to silence one of these discussions.