Yep, military has been saying for MONTHS that an attack on Mosul is coming, which can actually be helpful militarily, if ISIS responds the way that brass wants them to. Deliberate misinformation and psychological warfare are important parts of a healthy campaign.
I tend to agree with you, tactical deception can have positive effects for our side. If it were factual, it could cause the camel humpers to rush to reinforce and move fighters around. We can see every move they make and knowing their order of battle can make a big difference.
Then again, the release could have been ordered by the fascist Kenyan just to give his murdering friends a heads up.