Zoglins are able to move despite there being no player near them. This is a not intentional per the resolution of MC-47533. This is not as problematic for a hostile mob to move without a player near them as with passive mobs as zoglins can despawn, but it is still probably not intentional.

Some mobs which have complex actions are exempt from this rule such as sniffers (the have to move in order to be able to dig up blocks), but zoglins don't have any behaviors that require them to keep moving aimlessly, so they shouldn't be except from this.

To reproduce, find an area to spawn pigs, then find an area to spawn zoglins where they won't attack other mobs. Go into spectator mode, noticing that the pigs will stay still, but the zoglins will continue to walk around idly.