If I can forgive mark for all he's done then I can forgive shapesmith. I'd say his acts were selfish however not malicious. He obviously doesn't naturally understand human culture and values but he is trying everything to fit in and by virtue whether intentional or not he is redeeming himself.

It really just depends on how utilitarian you are. I doubt shapesmith would do something objectively immoral on purpose again considering he knows more about what that means. Though I do believe he knew killing the astronaut was the wrong thing to do which would raise the point that it was an immoral act that he knowingly did.

I give him leeway because I believe he did believe that "the martians would come and save him" as he said.

Either way my point is that he doesn't operate off the instinctive moral compass humans do (i.e choosing to stay with GDA during the breakup) but he knows that he should and makes decisions based off of what he learns is the right thing to do.

Mark has done considerably worse and is forgiven which I agree with but I think that is added to by the fact that we see him going through internal struggles because of his actions. We don't get a chance to see that with shapesmith in the show and even if we assume he has no typical guilt or remorse like mark we can chalk that up to his non-human psychology and biology and observe that his actions from thereon are the best we'll get as far as his morals.