Dr Peter Stevens is the scientist who created the cold sleep capsules. Being a scientist, Peter is extremely observant; despite the confusion and the panic, he still took note of the fact that of the survivors of the initial monster attack, only the Senator and Kasumi attempted to run for the elevator. The others didn't, and Peter believed that they may not have attempted to escape to the elevator because they already knew that they would be facing certain death.
However, this appears to be a mistaken leap of logic: Katherine attempted to run, and was knocked down by the other panicked Medusa victims; Peter and Ron stopped to make sure she was all right; Tim was too frightened to run; and Marco, of course, was the only one who had any idea what was happening.