That's 100% wrong. The calculation is based entirely on the position of the person attempting the shot and the context, so players at different clubs would be given the same expected assist score as long as the position of the shot and other relevant contextual stuff are the same. Whether or not a goal is scored is irrelevant to the calculation. It's as good a measure of the potential of the opportunity as you will get.
This is the sort of info that's invaluable in unearthing hidden gems. If recruitment teams went on goals and assists alone they'd potentially miss out on players with greater potential.