Eraser is a great product - and does an excellent job of removing residual polishing oils, dust, fingerprints, smudges, etc. before applying a coating. I personally would not rely on it solely to remove a wax or sealant. It may do that, if we're talking about a wax or sealant that has been on the car for quite a while and has been substantially degraded from exposure to the elements, but in the case of a new car with some type of LSP put on it at the dealership prior to delivery I would be skeptical. Eraser would not be a substitute for a chemical paint cleaning product in my view...
I completely understand the desire for "easy" and using something that you may already have, but the key to maximizing your coating as TMQ points out is to apply it to clean paint. You don't necessarily need PBL cleansing lotion for a successful application of the PBL coating, but you do need to start with a clean surface for the coating to bond properly. You can get there several ways including polishing the paint (which surprisingly most new cars need, do to the way they are handled once they leave the factory), or via a chemical paint cleaner such as PBL cleansing lotion if the paint is in good shape. Alternatively, you could ask the dealership to skip the new car prep which would mean there is no "old" LSP to remove prior to coating. In that case Eraser would work just fine as your coating prep if the paint is in satisfactory condition (i.e. no swirls or scratches you can't live with)...
Just my two cents.