I'm not recommending the following tour company, but they require a tripod on some of the tours. Some of the information on the web site might be helpful for you. A friend passed along the information a few months ago when I was planning a trip to northern Arizona. I didn't have time for the canyons, so I don't have personal experience with the company. The reviews overall are positive. There are also some negative reviews that seem to be somewhat consistent in what they're reporting. Sometimes it comes down to the tour guide that you're with who can make or break the experience.
In all my years of traveling and taking photo tours I have never encountered a firm that required
Many have recommended such gear but never required it. At the other extreme I've done some tours where they told you it would be made available so you didn't have to bring your own!