Then Ripley and Bishop would have done something about it when they found Hicks. They could only freeze him at the moment, but the facehugger could think they had more tools or whatever. If it had attacked right away, the events on Alien 3 wouldn't happen, so the others would have made it back to Earth, remove it maybe and the aliens would lose.
Maybe royal facehuggers are a little different, more cautious. We don't know how facehuggers behave with the other aliens, the Queen could have told it to standby.