Here's how I would interpret the slide, doing my best to prevent hindsight from biasing my opinion (since we already know what happened, it's tough to do).
Bullet 1: We looked at all the model data
Bullet 2: The model tends to predict deeper penetration than what we see in practice.
Bullet 3: The model penetration is related to particle velocity
Bullet 4: The penetration is related to the particle mass and surface area (they say volume)
Bullet 5: The foam is soft, so it takes a lot of energy to penetrate the hard ceramic tiles
Bullet 6: It is possible for the foam to penetrate the tiles, though, given enough energy
Bullet 7: If the foam does penetrate, it can cause a bad day
Bullet 8: It doesn't take much beyond the penetration energy to cause a bad day
Bullet 9: We haven't run tests that match the conditions of the strike so we don't have good data
Bullet 10: The foam piece is much, much larger than the stuff we tested
Given that, I would summarize it to say "The foam strike is much larger than what we've tested. All we know is this may mean there was significantly more energy involved, and if it's above the penetration threshold it can be bad. But the model seems to be overly conservative regarding penetration"
Now, the difficult decision is in the constraints. The astronauts didn't have the fuel to get to the ISS. They didn't have EVA suits to attempt a repair or evaluate the damage. There was no plan in place for a rescue mission. Atlantis was being prepped in FL, but was not currently ready. The astronauts probably have, at most, 30 days of oxygen.
Option 1: Allow for re-entry. Some had pegged this at about a 30% chance of success, but I have no idea what that is based upon.
Option 2: Scramble Atlantis to try a rescue mission. This is very risky for a number of reasons. Atlantis wasn't ready, meaning it would have to be rushed, increasing the chances that errors occur. Also, this type of mission was never attempted before, where two Shuttles are within spitting distance and astronauts have to migrate from one to the other. In order for the timeline to be feasible, a decision must be made within 1 day, 2 tops. This would then potentially risk two Shuttle crews instead of one, with an inherently risky mission.
I don't know what other options were available. Given when it occurred in launch window and how long it took to understand there was a problem, an abort wasn't possible. Shuttle did not have a launch abort engine like capsules do. Keep in mind, these decisions have to be made under large amounts of uncertainty. The extent of the damage was not fully known. People could scramble to run additional tests to gather data, but by that time the window on Option 2 may have closed. It's easy to arm-chair quarterback this after the fact, but there weren't good, clear options at the moment.
