It seems that open sourcing it while it is growing up actually makes more sense. If you want community involvement, ideas, testing, contributions, and so on, then hiding the project source is antithetical to why most people participate in open source in the first place.

Open source can mean more than just a license. It should mean more than just gifting a code base once you think you're done.

I don't mean to come across as bitter or entitled. I just question the value of waiting till the last minute. For now, the promise only stands as a way to pull people into the fold. I've seen this kind of promise many times before in projects much like this.