Agreed. I'm no Trump fan (I think he's a walking, talking, orange threat to our nation's wellbeing) but faithless electors should be illegal. And the electoral college should be made proportional.
I agree on the proportional concept of electoral votes as long as it's not done by who wins each congressional district, because that would pave the way for someone winning 60% in a state and getting 1/3 of the EVs.
As far as this situation it should absolutely be illegal, but it also shows the flaws of the electoral college--it is realistically possible that if the election is close enough, a small group of people could deny the winner their victory--EV's should be more of a point system rather than leaving it up to actual people who may or may not follow the rules.