Yeah, a slide like that would have been fine; fundamentally the slide is exactly like an academic paper in that some of the most interesting implications are just banal statements of the numbers in the data and qualifiers. In fact, the slide is much better than the academic paper... it doesn't contain much in the way of irrelevant data and qualifiers.

In practice Tufte and bloggers and commenters are retconning messages engineers not possessing foreknowledge of what was going to happen didn't wish to convey. The slide isn't supposed to say "no reentry" not because engineers don't know how to say no using PowerPoint, but because what the engineers are actually saying by selecting those points for consideration is "damage is theoretically possible but not in our simulations which test data suggests are actually on the conservative side; the test data is only at a very small scale though". If they'd dumbed it down, the slide would have said "it could go wrong but the limited data we've got suggests it won't"

I'm basically with you and let's be clear, I know nothing about the domain. But the word "limited" is doing a lot of work in that last sentence. Maybe a diagram showing relative size of the biggest foam chunk they'd tested vs. the size of the actual one would have been useful.