Or, as the far stronger side, the US could de-escalate. Not only is this the less-risky option, but it would also garner global respect/admiration for the US - something that has been in short supply for a long time.
How do you suggest they de-escalate (without the use of military posturing) a situation where DPRK threatens the very existence of two of our greatest allies, perpetually? I'm sure you realize that if DPRK is left to their own devices, they will develop a sufficient deterrent to simply saunter into ROK, and face no foreign intervention.
>I don't see what NK would gain from "nuking Guam," besides the end of their country.
Guam appears to be an internet hub for a few relatively important lines.
"The SEA-US cable system will link the five areas and territories of Manado in Indonesia, Davao in Southern Philippines; Piti in the territory of Guam; as well as Honolulu (on the island of Oahu), Hawaii; and Los Angeles, California in the continental U.S." [1]
It also raises the risk of unintentional nuclear exchange.
The world has come close to nuclear war multiple times as a result of miscommunication, equipment failure, or accident.
The more nukes world leaders are waving about, the greater the risks.