As reporters go, James Dunnigan is a great game designer. Actually, I have lots of respect for the man, but he's clearly not going to let facts get in the way of a good story.
Here's the environmental assessment report on the Propulsion Replacement Program (PRP). PDF format, 2.8 megs.
As noted in the report, the motors must be replaced if the Minuteman force is to remain viable through 2020. The environmental stuff is incidental to the replacement program, and environmental considerations went into the design of the new motors to make them "more environmentally safe in production, operation, maintenance and disposal." As one commentor at the strategypage.com site notes, operation is likely to mean test-firing. Thus the environmental protections will help safeguard the health of Americans who live downwind of the missile sites, and near the production and disposal facilities.
I don't know where Dunnigan got the info that the new motors will reduce the range of the Minuteman, but since they are fixed missiles with fixed targets, I don't see how it would matter operationally even if true.
Also--how is this relevant to the F/A-22?
How and when the Pentagon spends its money is very relevant to the F-22.