I don't know what the user's motivation is, but on the surface the advice is very much on point: security questions are insecure and shouldn't be used. Use a really strong password and have a valid email set so you can recover your account in case you forget your password. More importantly, having a weak security question on Bitcointalk allows an attacker to easily lock someone's account (see
https://bitcointalk.org/index.php?topic=1206977.0). You probably
shouldn't message him back about anything related to the security of your account - as other pointed out, that may be the start of a social engineering attack
On a side note, I don’t like that the forum doesn’t let you remove your e-mail address, and/or otherwise totally disable password reset by e-mail. (Yes, you can set a fake e-mail address; but then, you need to be careful to make sure it can never be valid. And that does not itself totally disable password reset by e-mail.) I’m not the only one. Lauda complained to me about that.
While I'm not sure whether it's 100% secure, an idea would be to set the email to like
noemail@noemail.test since .test (and similar TLDs) "is not intended to ever be installed into the global Domain Name System (DNS) of the Internet" (from
https://en.wikipedia.org/wiki/.test).