Did you use your forum account or an alt account to do it? If you have used your own account or a related business account, I see no unethical behaviour. This is a market where everyone competes with others, what would be unethical is to have some ring kissers to defame the competition using their DT status.
Anyways, I was wondering, since you are talking about plans for after december, can you tell me who runs altcointalk forum?