Not trying to play devil's advocate here but any vulnerability researcher must understand that finding flaws is only half of the job. You must also be able to successfully explain and make understand each flaw to even non-technical people or your work is somewhat worthless.
Now it's true that one can expect a reasonable technical skill from the Facebook person reviewing your bug submissions, but they also, as they stated, go through a lot of invalid and spurious submissions a day.
So in case you are hoping for a reward, you better make your submission as clear as possible before going mad and go public. Also you should at least retry and send additional details before giving up on them (reports do not mention whether the researcher "repeatedly" tried to explain the vuln to them.
IMHO the lack of patience from the researcher illustrates he really does not care about making Facebook (or anything) more secure. Only money drives him. This is perfectly acceptable but no quite the image for raising money as if he were a true whitehat.