I'm well aquainted with SDI'ing out of Peach's Uair string.not to sound like Swordgard but. uhm...
SDI?
However, even though chasing SDI increases human error and messes up buffering for frames being imputed, it doesn't necessarily mean the entire frame window will be negated.
It increases the chance of escaping, but the offending player can still follow it up with properly buffered Uairs.
At least the Nair and UpSmash isn't guaranteed.