a) the whiney brat who keeps on yapping kill kill suddenly cried and asks keanu to revive the cop. It shows that how horrible (and whiney) human are they are actually a compassionate being.

b) The scene with John Cleese. I think this is really the turning point of him wanting to give another chance to the human race. He (Professor Barnhardt)  actually able to ask back Klaatu on their moment of change.He says they have to change beause their sun is dying. Seeing he is the actual agent for change to entire human race really give him second thought. He actually accepts the professor as someone if not equal (in term of intellect) but somehow better than the race when they're solving the equation.

c) The whiney brat again. Even after how much he dislikes klaatu he ables to forgive and accept him. On a bigger aspect, The human race can cope with change and evolve.

d) When he saw helen cried. No idea(must have to be with even tho she's a scientists where everything must be quantified,proved and documented so it can believed, she still believes in something that are uncertain; like an alien who going to have a change of heart at the last moment) or probably his getting a boner seeing her crying

The way he stop the sphere? aww come on its like the dude's ride. Definitely there's a shortcut icon to stop the impending destruction somewhere in the sphere.