the problem is yours. your position was poor. first, a single airstrike is almost never a "strategic' action; it is a tactical one. second, as a former tactical intelligence analyst, I can guarantee you there's no mistake on a precision strike like this--ever. You could argue they thought the hospital was something else, but that would only fly if they were never given non combatant targeting information, which would be in every operations computer in theater.
on the other hand, is there a plausible rationale for attacking an MSF facility? I think there is, although I find the reasoning repulsive. first, the MSF doesn't distinguish in terms of "friend or foe"m which aggravates military commanders to no end. Second, if your opinion of locals in this part of the world is that they are all "terrorists-in-training", then you're going to think everyone is a combatant. This is actually explicit military policy--males that appear over the age of 16 are to be considered hostile or potentially hostile. If this hospital is treating them, the US command won't like it.
My guess is this is part of a larger campaign to pull out any third party with a permanent presence that could get in the way of a particularly nasty operation--say, a party that could provide a witness to crimes like Fallujah. This isn't the first time we've done this to nonpartisan aid organizations in war zones.
Edit: Just to remind you of an important context here: Kunduz was a major blow to th prestige of the Afghan government. There's already a major mobilization for a massive counterattack to retake it. I'm guessing someone wants no witnesses to what might prevail there.