What?
Aside from the fact that I find it doubtful that most evolutionary biologists ever believed that Bigfoot existed, let alone thought of it as the missing link. (I'd be inclined to say "any biologist," but chances are there probably is one such nutjob. After all, Michael Behe is a biochemist, but that hasn't stopped him from believing in "Intelligent Design" -- needless to say, you'd be hard-pressed to find many other scientists who agree with him.)
And even if the Loch Ness monster did exist, it wouldn't prove that creationism were true.
All that being said . . .
How on earth in the existence of the Loch Ness Monster more likely than the existence of Bigfoot? Although, to put it lightly, I highly doubt that either exists, I would think that that, if anything, the existence of Bigfoot would be more likely. To determine whether or not the Loch Ness monster exists should be much easier. You've got this huge giant monster confined to one lake in Scotland. You've got a large animal in a relatively small area. It can't escape and it can't hide. We have things like sonar and radar. If the Loch Ness monster exists it should be pretty easy to find. However, no one has found it. Now, to determine to the same degree of certainty that Bigfoot does not exist, you'd be looking for a smaller animal and you'd have to search all the wilderness on the planet near any alleged sightings. What's more, Bigfoot can run away or hide, while the Loch Ness monster can't. No one has found Bigfoot either, but by definition you would expect Bigfoot to be harder to find than the Loch Ness monster.
The claim that either exist is laughable, but I don't know how anyone can claim that the Loch Ness monster is more likely to exist. It's simply absurd.