Again, per the paper, the night sky is actually pretty luminous and nominally the bugs can still orient "up" with their top toward the night sky. If your red light was comparable to the illumination flux from the night sky you would see this effect.

It is really entertaining that you would appear to have a specific preference about just how bugs hit your face.

It's probable that the psychological effect of having the light on is distorting how they perceive the insects hitting. I think the only scientific way to deal with this would be to make a bug spraying machine that can spray bugs at someone's face in different patterns. It may take a little time to find the right pattern, but when the subject thinks it matches what they experience with the headlamp they could say "Yes! Yes! That's the one!" (or they could just put their thumbs up and smile if they prefer not to open their mouth)

I recently bought a red headlamp for night hiking because I wanted to try something that wouldn't kill my night vision (under a good moon I prefer to hike without a light as using a light kills your night vision and thus your distance vision) but if it doesn't draw bugs that's an extra plus. At the borderline I usually avoid using my headlamp because the bugs it draws are annoying--when something flies a couple of inches from your face it's very bright!