For background, as a few other commenters have pointed out, we get hundreds of reports every day. Many of our best reports come from people whose English isn't great - though this can be challenging, it's something we work with just fine and we have paid out over $1 million to hundreds of reporters. However, many of the reports we get are nonsense or misguided, and even those (if you enter a password then view-source, you can access the password! When you submit a password, it's sent in the clear over HTTPS!) provide some modicum of reproduction instructions. We should have pushed back asking for more details here.
However, the more important issue here is with how the bug was demonstrated using the accounts of real people without their permission. Exploiting bugs to impact real users is not acceptable behavior for a white hat. We allow researchers to create test accounts here: https://www.facebook.com/whitehat/accounts/ to help facilitate responsible research and testing. In this case, the researcher used the bug he discovered to post on the timelines of multiple users without their consent.
As you can see at https://www.facebook.com/whitehat, in order to qualify for a payout you must "make a good faith effort to avoid privacy violations" and "use a test account instead of a real account when investigating bugs. When you are unable to reproduce a bug with a test account, it is acceptable to use a real account, except for automated testing. Do not interact with other accounts without the consent of their owners." Unfortunately, the OP did neither of those things. We welcome and will pay out for future reports from him (and anyone else!) if they're found and demonstrated within these guidelines.