The concept is good...I just hope that the instruction to boil it for 3 hours was either a misprint or bad editing.
If you choose to cook a corned beef immersed in liquid (as is commonly done), once it comes to initial boil it should be immediately reduced to a simmer. The 3 hours cooking time does sound about right, depending on the size of the brisket you use. Brisket is a tough and stringy cut of beef...you certainly don't want to undercook it.
Having worked for a time in a deli, I can also offer this: If you really want to adapt this to the way NY's Carnegie Deli or Katz's do their amazingly succulent corned beef, you don't even want to immerse it at all. After the beer brining of the meat as described, at cooking time it should be placed on a rack over the liquid, in a covered pot, so the brisket steams rather than boils or simmers. You get the same (or better) tenderness as you would with cooking it in liquid, but the meat seems to come out much more flavorful with steaming.