Interesting approach. I am for a instant power down for a 5-10% burn fee. (Agree with @Jrcornel response- with multi-factor identification and and white listed accounts etc... as protection against hacks) - is a instant power down even possible on Steem, or is 5 days the quickest?
I’ll think of this idea more and give a more detailed response on my thoughts.
Whatever the decision is I highly agree to postpone the change until after the SMT hardfork.