I remember when most motorcyclists were motorcycle riders because they just didn't have the money to choose: We (I was one of them) either had a motorcycle or a car. And so "we" motorcyclists were on the road summer and winter, whether in sunshine, rain or snow.
And if someone was standing on the side of the road with a problem, it was a matter of course to stop and offer and provide help.
In the last 20 years, that has changed a lot. Hundreds of motorcyclists on weekends every hour, so greeting now is ridiculous. Some, no longer up for it, eventually mounted a plastic automatic waving hand on the handlebars.
Today, my greetings are very selective. I've learned to distinguish between life-style bikers and real bikers. The typical Harley rider with a new 1500€ leather jacket with the price tag still hanging off is not what we used to be. Nor are the horsepower junkies in screamingly colorful, skin-tight leather who have their wives pick them up in the rain with the trailer and have to have the latest model every year.
There are only a few left who are attached to motorcycling in the old tradition. We usually recognize each other and greet.
I do believe that in the beginning it will be a pleasure to meet other Grenadier drivers on the roads, so they surely wave to each other.
But I think it's a little silly to "vote" for a greeting or not. Time will tell. The day the first Grenadier driver ignores me when I'm standing on the road somewhere with a flat tire will be the day that whatever greeting becomes rare.
Unless the other guy has a "The Ineosforum" sticker on his car ;-)
I will however always greet (real) Defender drivers, as I do it today when on my motorbike. And they usually greet back.