I know he was young and didn't think about it but what he should have done is get into Valve network, watch it for 2 weeks, copy some source code to proof it AND after that say:

"Hey Gabe, you know what I love Valve and I love all of you guys. You are all my biggest heroes BUT you know your security systems aren't good. I hacked your system and it was quite easy. For two weeks no-one even noticed it. I DIDN'T steal anything but if you give me a job I will do my best to pretend such security issues and make your system as secure as I can. Would consider giving me a job?

I attached some source code of Half-Life 2 to proof my abilities.

I hope you all best and hope to hear from you back.

Thanks"

I really think that this would bring in the job.