I think this is a very interesting predicament. It seems to me that his draft stock will fall considerably for a few reasons:
1. Sam Bowie and Greg Oden. Drafting big men in the first couple of picks with injury histories or who look like old men when Michael Jordan and Kevin Durant are available will not only destroy your team and waste your owner's money (which apparently they just love), it will also get you fired as GM. One example from a generation ago is one thing, but the Oden one still hurts, especially seeing as Durant just earned the MVP trophy. If this report is true (which it really does appear to be), then Joel Embiid has officially become nuclear.
2. From what I can gather, this was during a WORKOUT. This wasn't even during practice or, much less, a game. If a player has a history of back problems (huge red flag) and then breaks his foot during a workout, of all things, you distance yourself from him fast.
And teams will do exactly that. He WILL fall to us, and my advice is that we bypass him too. I have nothing against him personally, and I certainly wish him the best, but we need to avoid him like the plague. If he does end up having a good or great NBA career, you deal with the fact that you opted out of the calculated risk for the good of your team.