Stating the Alien universe doesn’t have FTL is, frankly stupidity of the first order! The filmmakers should be fired.
Look at it rationally:
The Nostromo is on some STL voyage, hauling (effectively) crude oil. It takes, say, 30 years to get there and 30 back, assuming the ships accelerate very rapidly and travel at near-c velocities. If they don’t it’s even worse!
Ripley spends 57 years in suspended animation. Her rescuers takes years to get back to earth, even if they left right away (and why would they? Too much work for too little reward)
Somewhere along the lines a colony is built on LV426, which takes at least, a coupe dozen years.
Burke believes Ripley’s story, and sends a message to LV426. it takes decades to reach there. Burke retires and dies of old age.
“We’ve lost all contact with LV426”. How would you know? “Losing all contact” implies two-way communications. Or it happened decades ago, and the planet just “went silent”.
The Sulaco is dispatched. It takes decades to reach LV426
Everyone has been dead, including the Xenomorphs, for a hundred years by now. No percentages, no exclusive rights. The Sulaco heads home.
By now decades have passed on earth, and Weyland-Utani has been bought up by Parker-Hannifin, or Bershire-hathaway or Proctor-gamble and no one wants a Xenomorph anymore. Burke, not dead,
gets a job in the spice mines.
Meanwhile, young aggressive predators travel at sublight speeds to earth or Zeta Reticuli to hunt. By the time they get home, everyone they know is dead and they can’t impress anyone with their scalps.
People can say the Alien-verse doesn’t have FTL, just like people say Deckard is a replicant. They are simply, demonstratively wrong.