School classroom, athletic team, office, business, group of friends--- all of those take on a particular "culture". When I read those posts, that's how I saw it too. They were talking about the personality of the team regarding focus, discipline, drive, committment, etc none of which is tied to race.
That doesn't mean some haven't seen or used the term "culture" to be something racist but I'd be very surprised if it was more than very few.