Take a look at this incident from an entrepreneur's perspective. Let's assume you run a clothing business and you want to retain your loyal and big customers. So you start with deep discount package for your customers who will buy clothes worth 1000 grand during a certain period and offer fixed 30% discount to them for their next shopping session. You don't give the same to your small customers because they aren't profitable for you. It's business buddy! Big clients are the ones who give business to the exchange so it's no wonder Binance would want them to retain by providing such cash gifts! Nothing unethical or wrong here!
Same goes for banks as well. We have so many banks who provides preferential interest rates to their "ultra high net worth clients" just to keep their account in their bank. In a market bustling with competition, will always see such kind of preferential treatment towards the deep pocket individuals!