It's not really like we can believe their word on this sort of thing, actors and producers have lied before.
The scene is shown twice, in episodes 4 and 5, from very different angles.
Typically if an actor is wearing a prosthetic there is limited movement and a large amount of bush...lol.
But he is flying and bouncing all over the place and has close to no pubic hair.
The shots are also very quick, which is usual for an actor going frontal because they don't want to be on screen too long.