I'd be cool with seeing the support NM either dropping 9 fragments + rare mat chance -or- have no associated loot.

One rewards those who could be inside but chose not to. The other puts an onus on those inside to have some goodwill built up with those outside, or have groups outside dedicated to supporting them.

I honestly think tying outside NM's to inside fights is silly, but if you're going to do it, go all the way with it.

And if theres a thought of "we dont want people doing the first 2 bosses then returning and doing the support nm for more fragments" lock returning once raiden dies until BA times out or the support nm dies.