I would agree that I'm not sold on Jakob being a full time starter. For now, he has stepped up admirably, and his defensive efficiency stats back that up even if he has an off game here or there. He is probably better suited for a bench role, but he seems to perform best on this particular team at this particular time in the starting lineup.
Could the Spurs find someone better? Probably...but that doesn't change the situation we are in now.
The point remains...bang-bang plays happen all the time in the NBA. I've only played recreational and pickup ball, but that's enough to teach you how easy it can be to step in the wrong spot or be in the wrong place in the wrong time. I've been fortunate enough to only have a couple tweaked ankles and a knee bruise (falling on the concrete sucks), but going back to my point... happens in basketball. Some players manage to go through their careers without serious injury, others have careers derailed by it.
Blaming Poeltl for standing there is the same as blaming White for jumping and landing where Poeltl was standing. There is no point blaming anybody when it was clearly just an accident unless you just want to use it as vindication for your Poeltl hate.