I'm not familiar with the specific process. I've heard various claims that Android is not independently buildable, though existence of alternate Android builds suggests otherwise.

Taking the original claim at face value, viz "No they changed their development process to do it behind closed doors and release the code after final release" (<https://news.ycombinator.com/item?id=43778333>), then no, the process isn't Open Source.

The argument then becomes not one of definition (law) but of the facts of the case. Again: I cannot make a determination here, but your haranging wordofx appears misdirected and weakens your case. That's not saying you're not correct, but you're coming across poorly and unpersuasively.