[Cheburashka]

Zawahiri could have provided his own blood to have it splashed around the bombing site to fake his own death.
---
You're right of course.
But if there are odd pieces the odds of survival go down.

[monocle]

Zawahiri could have been injured and lost a leg or an arm and still escaped. There were reports some bodies(perhaps injured but still alive) were removed before authories arrived at the scene. Body parts at the scene would increase the probability of Zawahiri's present at the time of the bombing, but unless there is evidence of vital organs there is still the probability he escaped injured.