This is a bizarrely hostile attitude to have. Critique their work, not their age.
To be clear, I don't like this state of affairs. As suggested above, the best course of action seems to be to ignore the posting.
It's so inappropriate that in the field that's actually trained for this, they're disallowed by compact, even with extensive evidence.
Please stop.
The field trained for this is not refraining from this because it's hard to get right, but because it undermines the privacy promise they give their clients! not an argument applicable to people who do not have that professional reputation to uphold.
Of course you should speculate about mental health of people when it's relevant to the topic - it's a factor heavily shaping many people's behaviour!