I knew someone who was (tangentially) involved with that; apparently one of the biggest problems was that it came out during the height of the Megahertz Wars, and pretty much the first thing anyone asked about the AMULET was how fast it was, expecting a clock speed as the answer.

Given that the answer to that question for the AMULET was 'Errm...', they'd then just abandon it as a processor candidate as being conceptually too difficult to think about.

I wonder if the design could be reworked into Verilog or VHDL and used as an FPGA soft core?

If that was really what did it in then it shows a real lack of creativity. Synthetic Mhz would have been the way to go - just like how the EPA still gives an MPG rating to electric cars.