>For starters, in most places, warranty is a legal requirement and the manufacturer isn't allowed to void it for whatever reason they want.

This only makes the statement untrue if you use “can” and “will” interchangeably.

>More importantly, rooting is only a security risk in the sense that it increases the attack surface for exploits.

This is a good point. What even is “attack surface” anyway? Does anybody actually consider it when “evaluating security posture”? If I simply choose not to care about attack surface because I don’t want to, then doesn’t it simply become a factual nonissue? There are no answers to these questions