How difficult is it going to be for ARM to deny willful infringement of '336?

From a previously posted post:

...ran a search on the very title of PTSC's patent 5,809,336 "High Performance Microprocessor Having Variable Speed System Clock."

Low and behold, among the returns were a couple of very old sites (1996 - one year after PTSC filled for patent 5,809,336) by ARM (Advanced RISC Machines Ltd) and Digital Semiconductor -- development collaborators of Intel (among many others). In the text it goes on to describe features and functions of this NEW Intel StrongARM SA-110 Microprocessor, the FIRST member of the StrongARM family of high performance, low power microprocessors, the very foundation in which most of their microprocessors are built today. (registered trademarked - NOT patented)

I would ask ARM just one question after reviewing their patents,

Why didn't you patent the technology? 

Be well