I really don't think it's a matter of being worried about personal score or avoiding combat, I just don't think people want to fly an additional 20-40 minutes after dropping their load.
That is not my experience. 90% of the time I have climbed and been in position to intercept buffs before they drop. The last time a guy bailed is a perfectly average encounter for me, when on Monday at 30k, a buff is about 5 minutes from his drop when I obtain Icon range on his dead high 12 and the instant that happens, poof he bails.
I do not want players to be shamed for bailing, but know this. I film every sortie and when you bail on me I review the film and I know who you were. I don't PM you about it in the game or here on the boards. You, (the bailer) know you did it, and I know you did it. In my opinion it's poor sportsmanship and that's how I will think of you for a long, long time. Should you pass away and your people are fondly reminiscing about you, I shall be silent and remember you as this type of person.