
apparently needed more on the ground testing before putting an expensive payload on it
just saying, if you want the thing to light, you need to make sure it'll work with sufficient on the ground testing. it's the kind of thing NASA has done a LOT, after all. Granted, getting LOX + anything to light up takes SOME doing, especially if the engine is designed to be re-started in space.
But i expect it COULD have been tested on the ground, first. Tested ENOUGH TIMES to be signed off as "reliable" at any rate.
Confidence in this new engine is a *bit* lacking.
(and they didn't give any details as to why, either - pumps failed? No arkie sparkie? Not enough accelerant if THAT was used? Or maybe they just do not know???)