So if my band wants to send out free MP3s of our songs on the internet to get started, and encourage others to send it via Bluetooth to others for free, that's totally illegal? According to Apple it is... Just because you have a religious belief doesn't mean I should have to live by it. Same applies here.
Wrong. If you brick your iPhone you have no recourse but to return it to Apple. Right now Apple doesn't do a postmortem to see why it's dead, but if they change that policy, you're screwed.
They also don't have the device phone home, or intentionally shutdown if they find a root kit, but they could if they wanted to quite easily. The N900 has no such mechanism, and because they intentionally expect people to get root and alter their device, there's no worries about voiding the warranty if you do.
Jailbreaking an iPhone is taking a large risk. Up till now that risk has generally not had a harsh consequence if things went wrong, and that may or may not change in the future.