Two Legs Good, Four Legs Bad?

http://www.bfro.net/GDB/show_report.asp?id=41318
At the link above is a BFRO report of a sighting/encounter in Champaign County, Illinois.
The witness reported that a 7 foot tall, very hairy and beefy animal was observed walking out of
a ditch near a roadway, firstly on all fours, but then leaving the scene on two legs.

Encounters with Bigfoot that include a quadrupedal event are not uncommon, but they seem to be less common than the standard bipedal account, and so it is worth wondering about why an animal capable of the advantages of two legged ambulation might still go down on all fours.
Great Apes are pretty much the opposite of Bigfoot, wherein they will spend the great majority of their movement using their feet and knuckles, opting to stand more erect only on rare occasions.
The anatomy of Mountain Gorillias, for instance tends to preclude them from a comfortable, efficient ambulation due to the physical bulk of their upper torsos vs. their less developed legs and hand-like feet, whereas a typical Bigfoot description includes a more human-like proportion of upper body to lower body and a forward facing, in-line big toe and oversized foot.

The premier authority on this subject, of course, is Dr. Jeff Meldrum, and according to Dr. M, Bigfoot casts indicate that Sasquatch has evolved to favor bipedalism as opposed to modern apes.
"By examining the various footprint casts, I have identified clues that reveal the skeletal anatomy of the foot  --  its joints, proportions and dynamic interactions with the ground. Each cast or footprint photo has the potential of adding an additional piece to the puzzle, or to further substantiate an inference about the functional anatomy of the Sasquatch foot.  Rather than simply an enlarged human foot, the Sasquatch foot displays a unique combination of more primitive ape like features combined with specializations for bipedalism.  The prospect of a large primate that may have independently evolved bipedalism is intriguing in several respects, including a better understanding of primate diversity and the origin of human adaptations."
So if bipedalism is an accepted goal of evolving higher primates, why would Bigsquatch bother with reverting to knuckle dragging?

The answer could be in the advantages that a lower body profile might provide for a creature that is said to routinely stand at 7 plus feet.
Theory: In thick forest growth, a bear will have an easier time negotiating it's way through the bush. It's pointed nose, narrow shoulders and low center of gravity help it to forage at the forest floor, and while it can stand on two legs to source food that hangs from vines, bushes or trees a bear will do just fine as a quadruped.

A Bigfoot that lives in deep forest areas must be able to move more quickly than a bear to catch it's prey, primarily deer, and to travel where deer live, it would benefit from being able to go to the ground to give it more stealth.
The problem with this theory is that we are talking about a particular branch of evolution that would allow for Sasquatch to do this, taking millions of years that way it took for the rest of the animal kingdom, but without providing a fossil record.

The brings me back to the crazy part: Bigfoot did not evolve here
He was 'brought' here and plopped onto the planet. Ok....tear me apart now.
But explain this in some other, credible way