I got it. There was another Bishop already on the colony. He hid in the shadows, watching, waiting. He was able to move freely in the hive. When Ripley finished freaking out and ran, he followed her and the queen with an egg. He hid in the landing gear. Him and the queen high-fived as they colony exploded behind them, and he got her pumped up to kick Ripley's ass. He hid away until it was all over and sabotaged everything. He's still on the Sulaco....waiting.