Paulides never says in the Missing 411books that he believe sasquatch did it, although he did write at least one book on bigfoot. He leaves it strictly up to the reader to draw their own conclusions. He does say, however, that he was told by a park ranger that there were wild men in the park(s), whatever that means, and he does not go into much detail about it. Wild men in the parks, with furs/skins thrown over their shoulders, would not surprise me in the least. Hell, we have them walking down city sidewalks.
I just bought the book, Missing, written by his father. I have yet to read it, but Paulides and the father is/was having a hard time believing a cougar took the child, even though some "experts" have called it a cougar attack. It seems to me, from a lot of articles, books, forums I've read, many parents have a hard time letting go, they seem to NEED to believe their child could still be alive somewhere.
Another good book is Cougar Attacksby Kathy Etling. She recounts cougar reports from the 1830s to roughly 2001.