The reason this news is important is because Dubai, despite all its problems, is believed to be one of the safest places in the world. No one can deny the fact that crime rate is negligible here and terror attacks are unimaginable.
So when a terror threat is elevated for Dubai, this is really something to be worried about. I really wish and pray that nothing happens here and things remain peaceful as ever, but if something bad happens then that will damage the image of Dubai somewhat. It will no longer be the peaceful city where everyone prefers to live.
On a humorous note, this might be a rumor spread by someone who is interested in buying property in Dubai. Any bad news can bring down the prices of real estate and new investors can benefit from it.