Wouldn't United put them on the 1st available space, even if it is 3 or 4 days. OP wrote that because cancellation
was because of weather he would not be reimburse (to purchase a ticket later perhaps on another provider?). That does not sound like United policy.
It seems safer to wait for a ticket on United to Guam to open up since walk up tickets on other carriers would be much more
expensive when the storm passes.
Maybe you can find an Airbnb less expensive than a hotel while you wait it out. Good luck.