I don't think the person you were replying to was suggesting that any infosec people who fully support the researcher aren't real infosec workers. I just don't think he saw any who even claimed to be.
Defense in depth means every defense needs to be validated not just the outer layers.
PS: Further, if FB says they know about a bug then anything he downloaded could easily be in the wild and should be investigated.
What's really getting to me is the overwhelming number of responses containing idea that everything that isn't explicitly banned is permitted, despite the recipient saying "No" (even indirectly/without justification) at some point. How to deal with the grey area of consent is something that every adult should know, and it's worrying to me that so many here seem to feel entitled to whatever they can take as long as it wasn't explicitly forbidden.
Obviously FB should update their policy, but at the same time it's important that we as the community use this as an opportunity to learn and discuss where the implicit boundaries are, where one needs clear-cut agreement to proceed.
Consent is sexy.