A man wearing a white t-shirt and shorts is rock climbing with other people wearing blue hard hats.
A man in a whit shirt and shorts is rock climbing at a very very slow pace.
Climbing with other people does not mean climbing at a slow pace. The whole group could be going at a very fast pace.
Just because a man is rock climbing does not mean he is going at a very slow pace.
Just because he is rock-climbing does not mean he is going very slow