No. It seems highly likely, even to the point of almost certain, but it isn't exactly proof

But, most important, think about the potential of abuse here.
You could just happen to be a person who managed to "hack" the coinlearn.org web server, and now you're trying to gain access to his/her bitcointalk account as well.
Not saying that you are, but it's a possibility that should be taken into account.

That's why, among other reasons, the only acceptable proof of ownership can be a signed message with the key of an address that's certain to be associated with the account in question.