Ah, well that's the devil in the details. It wasn't merely one guy, there was a core of wikileaks developers who departed the organization all at once.

Second, they have made assurances that the wikileaks platform is in fact inoperable, given the state that the platform was in when they departed. By their account, wikileaks was not trustworthy enough to operate the platform, so they felt no inclination to fix it.

I am not going to claim first hand knowledge of any of these facts, and I don't know how the actual departure of Daniel Domscheit-Berg and co. actually went down. Assange has made statements contrary to Domscheit-Berg, and again, having no 1st hand knowledge, i can't claim to know one way or the other.

Assange has not, in any of the statements i've seen, addressed the current state of the platform, or how documents can be uploaded. On the other hand I haven't seen any prominent publication of how leakers can get documents to Wikileaks either. (happy to stand corrected if someone could point me to links!)