Megan, I think he may mean that SID gradients are based on all engines operating. As far as I am aware, there is no requirement to maintain 5% gradient in the event of a power unit failure as long as safe terrain seperation is maintained which may require a turn off the SID as part of a contingency procedure.
That's what I thought he meant too, although a standard SID is 3.3% and - as you infer - most airlines develope engine out SIDs because they, too, are often unable to comply following an engine failure.