Of course intent matters. If I run over someone with my car and kill them and it was deemed just a terrible but unfortunate accident, that is 100% different than if I drove over them because I intended to run them down and kill them.
The same applies to this case. He intended to access something he knew he shouldn't have had access to. Thus why he is guilty.
Yes, but in your example (where someone is killed) there is rather obviously an underlying act that may or may not be criminal depending on the intent. There are infinitely many acts that cannot be considered crimes regardless of how malicious the intent behind them may be.
Furthermore, just because someone feels that they have done something wrong does not make what they have done a crime. The law also must consider that action to have been illegal.
Hopefully, the appeals court will determine that accessing a public unrestricted URL cannot be considered illegal, regardless of the mindset of the person who might choose to access it.
The same applies to this case. He intended to access something he knew he shouldn't have had access to. Thus why he is guilty.