I think there may be a difference in the weight of an Alien that's 7 feet tall and one that's 10 feet tall. Also it's been living the life on a station with walk-in-buffet, it probably put on more than a few pounds.
Personally, the footsteps sounds like the arrogance of a dominant species, one that knows whose the boss. Also sounds like what a Queen or Praetorian would sound like on the prowl.