It depends on where they were.
There are certain parts of the Southwest Pass Fairways where going outside of it would not be possible at all due to the proximity of rigs/platforms.
I’ve seen her heading to and from Mississippi Canyon so I’m guessing (wildly) that area was where the collision occurred, either heading East or West.
If so I’m sure they will assign a portion of the blame to the OSV and a smaller portion to the ship respectively, if I had to guess, because there’s never a vessel 100% at fault even if you were anchored and someone runs into you…
What actions were possible and taken or not by both vessels, who can say? but rule 9 should have applied if it was indeed in a fairway but nobody seems to know.