As time and unfortunate accidents have proven there was no possibility of the shuttle ever escaping an explosion.

Of of any astronauts ever having a chance to escape it during reentry.

And they had plans for both.

One of the plans was for the astronauts to have jettisonable seats like fighter aircraft. But that was shot down when they realized that half the crew was on a lower deck and would have to escape directly into the large fuel tank.

the other idea was to have the whole of the command section serve as a lifeboat type capsule. if an explosion did occur the while thing would be armored enough to survive and could float down to earth on parachutes. Due to weight and the fact that the ship could be going well over a thousand miles an hour when an explosion might occur the parachute idea was tossed out also.

As for the escape during reentry idea it required the astronauts to get out of their seats and jump out the side door while in space suits all the while hoping the ship was in a steady flight path and not going over a few hundred miles per hour.

The SLS design actually has a chance of working but why they do not want to test it is beyond me. Maybe they think they are magic and don’t need tests.

I can understand NASA’s insistence on private space proving escape systems prior to crewed launches. Whatever NASA may be doing now, they have put people in space. And requiring proof-of-system serves the long-term interests of commercial space. In our risk-adverse society, if crew were to die because safety systems were untested or didn’t work, it would set manned commercial space back years, if not kill it entirely.