spool-up at 500
Then your airline and you are not complying with safe practice. The main issue is not that you have land flap at 500 ft latest - it is that the plane is configured in every respect for a safe landing and that includes engines at normal approach power. What if you had to go around from 450 ft? 12 seconds spool up time! And if they don't spool up symmetrically?
The airline I flew for did include spool up as part of the stable approach criteria, and even if they had not, airmanship and common sense dictate that engines spooled up is a pre requisite. Otherwise it is a glide approach.