As a general rule, if something is unknown, it is to be cataloged as such: unknown. Everybody who has a pet "explanation" are all too quick to fill in a gap with their choice, whether it's God, Bigfoot, Santa Claus, whoever.
Offering the excuse, "It could be [insert pet idea here]!" is not doing their argument any favors; especially when it carries as much weight as any other idea. Until we have actual physical evidence of Bigfoot (or whatever) and it's been (scientifically) tested in every way to where there is no denying it's Bigfoot (or whatever), there's no point in using the lame argument, "It could be such-and-such!".