Bluebird is an endgame mistake that involves p1 blowing up half the homeworld of p2 and allowing p2 to win specifically -because- of the destruction of half her homeworld.
That's not what I call the Bluebird Mistake. (I don't have a good name for what you just described, but clearly it needs one.)
The Bluebird Mistake is leaving 2 ships of the same color at your Homeworld without any other ships for cover in case your opponent drives 2 ships of that color into your Homeworld. More specifically, it's failing to notice that your opponent has the ability to send in those ships when you have a monochrome fleet at home.
Obviously I have a host of other replies to make in this super-bloated thread but I'll get to them when I can. (I've been out of town...)