I had a chance to read the whole PM with a cool mind, paid full attention and without been biased. When a PM comes from a lower rank member we usually think something is not right. It's the forum experience that led us to have this suspicious mind.
Read the PM posted again but without considering followings lines
Please get back to me stating how you improved account security. If I do not get a reply, I need to inform board administration for our all safety.
Captcha is useless as I use some trick I will only discuss with theymos.
This is what happened to me when I read
get back to me. The moment I read it, I had in mind that this is it, this user was trying to get information from OP and other users.
Read the full PM again. It seems the user's native language is not English. Some choices of words clearly tells that he used translator to pick the words. Yes I agree with buwaytress some words sounds offensive. But I feel that this was not an intent to get something bad from it.
The user asked you to get back to him, could be to suggest you to remove the secret question. If you do not then he will inform theymos so theymos can consider to remove the security question feature entirely for the safety of DT member. It seems he thinks DT members are the ones who need to stay safe so his all effort were to be sure DT accounts are safe.
They only sent the PM to those who had security questions turned on. Somewhere theymos also said that it is not recommended to use security questions because it locks your account and some other hassles when you try to recover the account.