Joe in state A asks a question online: "I did _____. Is it legal? What are the consequences? What should I do?" Jake in state B responds in a manner which, while entirely okay according to state B's UPL rules, clearly falls under state A's definition of UPL. Is Jake guilty of the unauthorized practice of law?
Joe does not have to exist or have asked a question: the issue can be reduced to the (dubious) premise that there is at least 1 state (A), not one (B) that Jake is in, where Jake's reply would constitute UPL. Jake is not guilty of UPL, because Jake is not in jurisdiction A. Analogously, if Jake in state B renounces his religion online, which is the crime of apostasy in country Z, Jake is not guilty of apostasy.