Not to butt in here Little, but that would not have been BB's decision.....it would have been the actual operator since BB does not run the trips per se but is a facilitator. I can almost guarantee that, unless you specified a specific guide, they would have booked yo with another operator. Could just have been a slow day all around. Happens from time to time no matter where you book, even when not slow season.
Next time ( hopefully there is not one) if you are the only one, and really want to go, and you can swing it, offer to pay for two ppl.