I'm not going to be very popular with this position but here's my take on it.
Any cell phone company, in this case AT&T, not Apply, has a right to set its own rules for the service. When you sign the agreement you are agreeing to their terms of contract. To circumvent or bypass their rules and terms of service is a violation and officially makes you a hacker if you use any means to bypass license restrictions. IMO, use of these software or hardware tools to hack your phone is illegal if it violates the terms of service. Additionally, any discussion or advice given on this forum is a violation of the "No Hack Talk" rules.
Now I did qualify this to say that it is an AT&T rules violation to hack the phone to use it in a manner not according to the terms of your license. But what about Apple? They sell you a phone, they do not lease it to you. You own the hardware device and IMO, it is your prerogative to use the phone in any manner you choose as long as it does not violate the terms of cell phone service (AT&T) You can use the phone as a hammer if you want, whatever floats your boat. NOW, if the use of jailbreak or other software enables a feature that is not permitted by AT&T, then it is illegal AND, AT&T must enforce it's terms of service. The only terms of service that they do not have to enforce are those that are also regulated by the FCC. The FCC has that obligation to enforce FCC regulation violations.
So, who the hell does Apple think it is telling you the computer you bought, the iphone you own, is a licensed technology? Well, lets be open minded for a minute and look at it the way Apple does. In addition to the hardware, iphone is also loaded with Apple's iphone operating system which IS a licensed technology. You may be legally able to use your iphone as a hammer but can you hack and modify, reverse engineer the operating system and any of Apple's software? Most likely not. SO, in this argument, I have to agree with Apple, that using anything that hacks the OS or reverse engineers it is a violation of your license agreement.
In addition, as long as the company, Apple, believes that Jailbreak is "illegal" any discussion of it here is a violation of the Satelliteguys.US "No Hack talk" rule.
IT doesn't matter about open source and whether you think it is a good thing, Apple is not open source so the argument is irrelevant.
Apple is not required to fix it's software to prevent the hack. If a bank doesn't lock it's safe and a bank robbery happens, that doesn't make the robbery OK. All it is required to do under the law is enforce it's no reverse engineer or modify OS rules by terminating a person's license of use and this may mean no cell phone service. It is required to notify all violators of this violation and issue a cease and desist order, to remove the offending software or lose service. I'm sure Apple has an agreement with AT&T to shut down the phones in violation .
Apple has already demonstrated it's policy with the iphone after the first hack when they bricked the hacker's phones.