Hmm. We went a couple years back in June while spending a couple weeks up at the North Rim. I'd made my reservations for the photographers tour well in advance and never heard anything like that from them. In fact, I was going to leave the wife and kids in Page while I went but they told us it was fine if they came along. All total, our truck was maybe 1/2 full...no more than 10-12 people.
Unfortunately, two of them, a elderly couple, made a habit of walking in front of those of us who'd set our tripods up. At one point, she tripped over mine and turned to her husband and said..."this is ridiculous, these people and their cameras are holding us up, they should have a tour just for photographers". The guide was a lot kinder with her than any of us would have been.
as i mentioned, that was just my experience. i had heard good things about them which is why i went there first, unfortunately on that day they were not pleasant to deal with.