Same here; I'm woman, and over 50. I use a landscape snapshot from an enjoyable daytrip for my profile photo. Is this, like removing graduation dates from a resume, an undesired tell?
Most companies would discriminate in your favor for both reasons. I suppose it is unpleasant to be the token woman or the token old person though. It sucks to suspect that you are being kept around to meet somebody's quota.
That’s a fair criticism. Having any kind of profile image I think is preferable to the default, because then it distinguishes you from someone who signed up a day ago. So it doesn’t have to be a photo of you, it could be a photo of your city, pet, some hobby etc.
Just something to humanize the profile, even if it doesn’t gender the profile.
Or you could conclude that this person is in there to just get stuff done, and couldn't be bothered with wasting their time to fill in their profile, or was concerned with how their data was used by Github, or is a woman, or is part of a minority group that couldn't possibly benefit from posting a photo, or... There's all sorts of reasons why people don't post their profile online, and factoring this into your hiring criteria is about as valid as using graphology.