While I agree with you that age discrimination exist at least in mild form, direct comparison with racial discrimination is excessive. In the extreme case, you won’t get shot by a cop for being old while arguably being black increases that probability.

But it’s not only race discrimination at play, there are other possible discriminations also more powerful than age, like gender, income or class.

So you put more weight to a discrimination that affects you the most because you probably don’t belong to other categories, hence the guess that you are a white male.

I am probably over reacting given the HN demographic and also because you did not do it in bad faith but just wanted to point it out.