He doesn't have to be authorized, no one on this forum "owns" the samples. The samples are owned by the malware authors, they own the rights to the sample and they freely shared them online to infect people, so anyone who obtains them can use them.
If he got the samples from this forum himself then he must be a member with 100+ posts as that's the requirement, or maybe he got them off someone else. But regardless, he didn't do anything illegal and there's absolutely nothing anyone can do about it because: we don't know how he got the samples, we do not "own" the samples.
Just because someone found them, put them into an archive and uploaded them after scanning them at malware analysis services and AV engine scanner services doesn't give us "rights" to the sample/s. Doesn't work that way