I don't see any impact to the risk of drunk drivers being on the road in posting a report about a check point. From a delay standpoint - after all, they are stopping every car and interviewing the driver - there is a lot of value in telling drivers about the delays that causes.
I don't know how other people report it, but I, personally, would probably try to focus reporting on the delay aspect of it instead of the checkpoint aspect - maybe use a traffic pin instead of a cop pin and wording in the description that makes it more about the delay than it being a checkpoint. The main reason for this is if any of the authorities administering the checkpoint also run Waze, they can remove the reports if they feel they are compromising the stealth of their operation. Same thing goes for speed trap pins, though I think their aim is to capture a much shorter interval of time.
This may all be moot anyway, since many DUI checkpoints aren't exactly stealthy, instead operating under the assumption that the worst offenders they are trying to target won't, in their inebriated state, be savvy enough to avoid them anyway.
Wazing the Garden State... one jughandle at a time.AM: New York City; New JerseyAT&T iPhone 5 / iOS 7.1.1 / Waze 3.7.8