eBay are'nt going to stop it when they are the ones responsible for inserting it

There is no need for disappoint if buyers were to realise the estimated delivery date is just that, not a promise 

All the seller(s) is required/responsible for is posting it within their stated handling time

Sellers are not responsible for the speed of the postal service any more than the buyer is 

Regardless of how many grey dots you want to leave sellers, blaming them for the postal service's slowness