Spoiler
Quote"The alien's abdomen had burst open, spilling a slick mess across the floor. It sizzled and spat as the acid-pool spread, but it was the things lying in the pool that drew Ripley's attention. Scores of them—maybe hundreds— spherical and each roughly the size of her thumb. They glimmered moistly beneath the flashlight beam, sliding over one another as more poured from the wound.
"I think we killed a queen," Ripley said.
"You're sure?" Hoop asked from behind her.
"Pretty sure—it's the only thing that makes sense. They're eggs. Hundreds of eggs." She looked back at him. "We nailed a f**king queen."
That happens in Out of the Shadows, maybe the Queen on the Sulaco was still pooping out eggs at the time and a few of them managed to grow up?
The Bishop theory makes retroactive sense, but I'm 90% sure that him not being on the platform with the drop ship was simply to give pay off for Ripley's "I CAN trust THIS android I guess" after a brief moment of doubt and was not intentional for anything nefarious in future movies.
Everything just ends up fan theory sounding, no matter what you do. The likeliest option is the Queen brought it up... That's another question to be answered, how and when did the Queen get on board the Sulaco in the first place? How and when did the Big Chap get on-board the Narcissus? Why didn't the Predators do a friggin X-Ray on Scar after his body was retrieved from an expedition to hunt creatures known to implant embryos inside of things?
Magical, magical plot convenience!