From reading the rules it sounds like Weyerhaeuser may not allow motorized access during extreme fire danger. But apparently walk in access will be allowed no matter what.
Read numbers 9 and 13:
https://www.wyrecreationnw.com/forms/LongviewSpecialConditions.pdf
I don't think those policies are in any way a guarantee that it won't close altogether. #9 could be interpreted that way, but it could also be interpreted as "Close" means closed period. I think if they think conditions warrant it, they continue to close too all public access. DNR fire levels will apply also.
#9:
"Access is 7 days a week from August 1, 2014 through January 31, 2015, provided that
Weyerhaeuser reserves the right to close or limit motorized access to the Property because of
extreme fire danger or other extreme weather conditions, including when undue damage may occur to roads."