You MAY be able to take EAB out of a smaller tree with 70% damage...but you still have a tree that has lost 70% of its canopy. What would you tell somebody who had a healthy tree but lost 70% of its canopy in a storm? I'd tell it it is toast. Long term survival is unlikely (there are plenty of other stressors besides EAB that the tree will face), and it will never be a good looking/strong tree again - EAB starts at the top so you loose the top/center first. I guess as a retailer, they are just looking to sell product. As a service provider, I don't flat out refuse but I go on a pretty hard sales pitch to NOT treat those trees. I know they are not going to be happy with the results, and I don't want to take somebody's money for 2, 3, 5 years just so they can be disappointed at the end of it all.