The only screenshot I can find shows a disabled account (not any rejected ads), and also seems to support Facebook's side of the story (you can see a banner in the background saying something about their "current balance", which would imply what Facebook said was true).
If I'm reading the picture correctly: Facebook collects and processes data about our medical conditions and sexual orientation. We've seen how FB allows ads targeting those metrics to be constructed - but FB also indicates it might get grumpy if those ads are posted.
Further, FB is not revealing who it makes that data available to or even explaining why it collect+processes our Med and SO data in the first place.
Does anything I've said here seem unlikely?
It seems likely to me that rather than wanting to hide these specific categories (but be willing to expose every other type of data collection they do on you), that Facebook doesn't allow these specific two categories because of the significant negative social/legal consequences if they get them wrong.
They are very likely trying to avoid gay users getting an ad that says "You're straight, join my Straight only dating site" or an ad incorrectly diagnosing users with a disease they don't have.