Unfortunately, there is no single device you can look to to enforce stealth logic on ADS-B traffic (Garmin will not likely devote a lot of time to algorithms that make traffic invisible) plus even if there were you'd have to figure out how not to blank out fast jets where 2km is probably not appropriate.

Then there is the issue of monkeying with the FAA's traffic system.

It may or may not be required for gliders, but it certainly will be available and given its usefulness for power traffic avoidance, do we really want to ban it?

It's tough to be King Canute - lots of things to worry about.

9B