You're also looking at one flight in isolation: without the interaction with other traffic in that area at the time, there's no way of assessing why decisions were taken to fly that profile. I would hazard a guess that the strike either happened, or became apparent, at the level & those involved decided it was best to maintain that level, but without an airspace map & the traffic at the time, a guess is all it would be. As to why the need to hold for 30 minutes, either as above, or assessing the different options before deciding to divert, I imagine.