Yep; the guide requirement is only in National Forest Wilderness Areas. Here is the question & answer from the F&G website:
Is it true nonresidents cannot hunt in national forest wilderness areas without a guide?
A. Basically, that's right. Wyoming statute says nonresidents must have a licensed guide or resident companion to hunt big or trophy game in national forest wilderness areas. The resident companion will need to get a free non-commercial guide license from a Game and Fish office. The law does not prohibit nonresidents from hiking, fishing or hunting game birds or coyotes in wilderness areas. Only nonresident big and trophy game hunters must have a licensed guide or resident companion.