[singpilot]

The ceramic spacers were there to prevent the tiles from being 'battered' on ascent. They are not needed for descent. Normally they do not loosen and protrude (or at least, no one has seen them before, this being the first real inflight inspection). The worry was that the laminar plasma flow in the highest heating time would be disturbed by the protruding material and cause the wake of the plasma flow from the protrusion to impinge on something downstream, burning it.

The tiles were so fragile to the touch, that the loss of flexibility working in the space suits attached to the footstep of the 50 foot long robotic arm would have made pushing the material back into the gap problematic. It wasn't needed, the idea was to remove it, or worst case, cut it so as not to impede the laminar crossways flow of the heated plasma.