(That seems to be the case on any dive that has more than one group with it. I don't get it - why hire a dive guide to ditch them???)
I know that for ME, the Dive guide exists to be 10,000% sure the boat is found again. I do not need the guide to find things or for underwater safety/back up. I also find that sticking right next to the guide makes for a slow/boring dive as the guide is limited by the least experienced person in the water.
I DO let the guide know I will not be staying right on top of them but I will be keeping my eye on them. Typically we will discuss a estimated turn time and some type of signal so I know they are ready to turn back.
I have never had a Guide have problem with this arrangement. IMO, again...IMO, a guide is a nice bonus but any diver should be self sufficient enough to dive on their own. THAT is one of the main goals of the WRSTC standards that all dive Agency's create their programs around.
"Open water certification qualifies a certified diver to procure air, equipment, and other services and engage in recreational open water diving without supervision.........A certified open water diver is qualified to apply the knowledge and skills outlined in this standard to plan, conduct, and log open-water, no-required decompression dives when properly equipped, and accompanied by another certified diver. "
If anyone NEEDS a Guide then they should reconsider the training they received.