Whatever transpired could have been far more subtle than, "gimme macbook, get story". For example:
"So glad to meet you. So happy to be your friend. Is there any way we can help each other out as friends? I love to help people out. I can give slots at my conferences, and I know a lot of bright kids looking for unpaid internships, and oh by the way I do some writing for TechCrunch too. Do I need any help? Well, I always want to hear about good story ideas and meet other interesting people. As my boss Michael Arrington has said, send us scoops and we'll think fondly of you and be more likely to report on you later! Also my side projects are hurting for equipment. You know, Company X gave us a projector when our old one broke. Why, yes, that was the company I wrote about on TC last month."
That is, the behavior could have been on the same continuum of "we know everybody, we trade favors, the old rules of fastidious disclosure of every slight-conflict-of-interest can't possibly work in this new world" that Arrington himself has used to defend his own practices. The companies that did 'pay' may have thought of it as just cementing an important friendship, not an explicit quid-pro-quo. Brusilovsky may have gone too far, but in the ways 17-year olds often do, because they understand only some of the patterns of their role models, without all the subtleties and limits.
That would explain both Brusilovsky's vague 'mistakes were made' and 'a line were crossed' phrasing and TC's reluctance to be more specific in allegations or shaming the favor-traders.