I agree, he seemed to only get personal when he knew the developer, and it seemed like it was mainly because he knew that they knew better, but were still submitting bad patches anyway. I still remember seeing an email response to someone who was just starting college and was telling Linus that he thought the way they were using spinlocks in the kernel was wrong. Linus knew they didn't know any better, so he didn't insult them, and went into a lengthy email about why they were doing things the way they did, and how the student's professor had taught them wrong.

Even though Finns can be much more blunt than people are used to, I think he recognized a while ago that he was going beyond being blunt. During a conference in Australia, someone asked him about how people perceived his attitude and it's effect on the kernel community. He told them that he's not a nice person, he doesn't know why people think he would be, and that if people enter the community with that in mind, they'll stop feeling like they're being personally attacked.