I'd say it is totally legitimate to give information about developments exclusively to backers of a kickstarter-campaign and to expect them to keep it private. They are involved with their money (and have proven their strong support for and interest in the product by pledging) whereas you have no relationship to the company aside of curiosity and obviously a deep desire for blaming the inventor. What relevance does this information have for you? If you are that curious you could and should have backed the campaign - then you'd be informed as well... If any information given internally to the backers would be published on the internet immediately the consequence would be not to give internal raw information that is not for the public to the backers. This would be a step in the wrong direction I suppose.

If you think this is wrong you should maybe start publishing secret and internal information from your employer on the internet. Maybe someone would be interested in that and - according to your argumentation - there is no reason why this information should not be published... And you could request any manufacturer of any product to publish the internal information from their R+D-departments as you need to know what they are working on.