Greg,
What is the purpose of this flex? If it is physical protection of the NM cable, it is not one of the methods mentioned in 334.15(B), though the AHJ does have the power to make this an "approved" method.
If it were me, I'd want a fitting on the end to protect the NM from being damaged by the cut end of the flex.
The chance of this cable being damaged is probably fairly low, but I do like the idea that someone went to the extra trouble to add a little more protection.
Tom
