It's hard to say what the folks at the Idaho Conservation League are thinking. They apparently told the local TV station that they can "potentially support" (TV news anchor's words) the plan. The representative quoted only said it was a "much improved proposal," though that doesn't make a lot of sense since the proposal doesn't seem to have changed since it was first released to the public over two months ago.
On the other hand, the Idaho Conservation League website contains this press release, which does not indicate that they approve of the governor's proposal.
Reading between the lines, it looks as if ICL has decided the vaguely worded protections offered the 8.7 acres of roadless lands are good enough to let them look the other way on the 500,000 acres of roadless lands that will be more or less turned over to industrial logging.
One problem though is that the "protection" offered those 8.7 million acres seems pretty weak at least in the 5.5 million acre backcountry designation (permanent roads will be permitted "based on long-term ecological need," for example . . ..) and another problem is that this fight was never really about the full 9.1 million acres. Virtually all of those acres are roadless for a reason: they are too high, too dry, and too cold to grow much of anything that anybody would ever want.
If you have ever been up in the Lemhis or the Lost River Range, you can see why that country never saw much logging, and hence never got roaded.
From where I sit, the Governor's plan looks like a disaster. The 500,000 acres that will be given up are some of the last, best, forested country in the state, including the infamous Cove and Mallard roadless areas that were so bitterly contested by Earth First! back in the early 1990's.
The governor's plan is available here.