If you are still looking for a solution, you can do it like this:
IsGestureEnabled = false;
You can continue to use
await Navigation.PushAsync(new PageWhichWontOpenTheMenu());
, RootPage (MasterDetailPage) OnAppearing :
protected override void OnAppearing(){
base.OnAppearing();
(Application.Current.MainPage as RootPage).IsGestureEnabled = false;
}
, , !