Consider this:
If these creatures exist, it would be difficult to accept that government hasn't known it for a long time. The Indian Wars ended in the early 1890's, so by that time, the federal government had a really good handle on the legal and cultural difficulties of negotiating with aboriginal peoples, and almost all Indian peoples recognize sasquatches as a race of wild people.
The behavior (or, more accurately, the absolute absence of any and all behavior) of both California and federal governments after the filming of the PG event, even unto today, goes so beyond suspicion as to virtually scream out guilt. Both the California and federal government bully their way into every issue imaginable from the amount of water a urinal uses to the inspection of mattresses, yet we are to believe that they care so incompletely about the PG film that neither has ever so much as uttered a peep?
Sorry. I lived a full life within government, and I can't accept that possibility.
Therefore, I'm forced to believe that not only do they know that they exist, but they have conducted some study, or have closely monitored certain scientists or other appropriate people who have gathered intelligence on these creatures. There's no way they'd simply ignore them without gathering intelligence on them.
Thus, if somebody is making headway with these creatures, and if government wants to keep these creatures low key, the researchers might be enticed to conduct their work quietly. A bit of funding and counseling might be proffered. It wouldn't take much to convince capable researchers to keep quiet about their knowledge. Simply reminding what "discovery" might mean to these creatures could be enough for researchers to continue their work quietly.
I believe it's very possible that people might be doing the Goodall/Fossey thing with sasquatches as we discuss this, and it might not become public knowledge for another few decades.