Well, they came up with something that doesn't harm anyone since the Supercharger network provides free energy, he's taking advantage of an exploit so, I wouldn't say that what he's doing is wrong. But the thing is, this is going to bring more problems to Bitcoin, if this thing goes mainstream and makes a lot noise, it will eventually bring a lot of unwanted attention, and it will give people more reasons to attack bitcoin.
Tesla owners can do whatever they want with their cards, but I think this is not going to end well.