I've thought about this from a slightly different angle. There are places I ride thru where a "Cyclist Ahead" notification on Waze would be an invitation to find and harass said cyclist.

But, how about an alert when there is an organized cycling event? The route is established, DOT and local police have issued permits as needed. Why not a notification "This route is going to be clogged with bicyclists today, wouldn't you rather use that empty road over there that might add 5 minutes to your drive"?