Spoiler: NO. No one can access your account with just the secret answer. This will only lock your account - as explained in the previous page. Please read the whole thread before making a new post.
I never tried/used secret password and I don't plan to use it for unknown reasons but if no one can access your account by just using it, why it says "To help retrieve your password, enter a question here with an answer that only you know. Using this feature is not recommended. Anyone who guesses your secret answer will have access to your account. It's like a second password."It means anyone who can guess it will have access to the account because it's like a second password and is used to retrieve the account. I'm really confused which one to believe. But I don't want to try it myself.
But actually, I've set a secret question in my account before. I just forgot what's the answer
I've read the topic about this secret question in the link you have provided in the first page but I'm just wondering why the description says different. Well I believe you now as there are several members who already tested it out.