What could they do once they were in orbit? They don't have in-flight tile repair capability. That is a specialized operation only done on the ground. They couldn't reach the ISS. Columbia doesn't have the engine power for that height of orbit and anyway the orbit was set up for this mission such that the ISS was not within reach. They had consuambles for a set time. Sending another ship up to rescue them in time probably wasn't possible. We don't have these things lined up on the launch pads ready to go whenever we want.
The only thing I have heard suggested was changing the re-entry profile to that that damaged areas of the heat shield didn't get as much of the heat load as they normally might. But there are limits to that. There's no way you can completely avoid heating in an area. In fact, the gain maximum heat rejection you generally want to distribute the heat load evenly. Shielding one area means other areas are likely getting hotter.