Well, you just ASSUME they were guns. They could also be copies of NMS multi-tools and include mining laser, scanner and terraforming tools

Secondly I'd like to point out that having some Space Hippies dancing through an Brain Tree Field and sniffing at alien flowers probably isn't the most engaging gameplay you'd want to put into your first announcement trailer (unless said Space Hippies suddenly die a violent, choking death from the poisonous atmosphere they just inhaled

)
A bit more serious:
I agree with your concerns about weighting the different playstyles in a first person mode. I'd love to go exploring ruins, caves, derelict ships/settlements on foot. I'd also love to shoot the occasional robot, alien or pirate while doing so. But the balance needs to be right. When I find a derelict settlement, I want to be curious about it and explore it, without knowing what awaits me. Discovering messages that tell the story of the place and the former inhabitants... But just seeing the POI from orbit and knowing "Haahaaa, pew pew Leg Pirates!" would kinda take the fun out of it. If Space Legs just equal FPS combat, I'm not interested. If they offer engaging gameplay for various playstyles, I'm all in.
My second concern is about the pace of the FPS part. I don't like the modern day fast paced CoD like arcade deathmatches. Every once in a while I do some PvP in Destiny 2, but that's already too fast for my liking. I like more tactical, slow paced games (which would also better suit the slower paced exploration gamestyles). Think of Arma 3, DayZ or Swat 4 (gosh I'm old). PlanetSide 2 would be a middle ground I could still live with.
But really, I do not believe the modern day fast paced, arcadish FPS shooter games would fit into the rest of the game and I honestly believe that FDev knows that. They aren't as inept or dumb as some forum members believe them to be.
But so far we do know absolutely nothing about the content of Space Legs at all. I'm crossing my fingers the Dev Diary in August will deal with that topic and give some much needed info.