That means Apple must cover jailbroken devices under warranty too. Sideloading Cydia will be even easier now. Apple must support all device configurations now.
Cydia is just an App Store for modifications, right? Don’t you also need to exploit a vulnerability in the OS to get arbitrary code execution? Doubt modifying the OS will be covered under warranty.
Software modifications are already covered under warranty in Europe too as long as they didn’t cause hardware issues (and it’s up to the manufacturer to prove it).