What to do with bulldog while at work?

Unfortunately, this is a sign of a breeder not doing their homework (which makes me wonder if this little guy was bought from a backyard breeder...which will lead to major issues later for your friend). At any rate, maybe your friend would consider crate training? I wouldn't recommend leaving the little guy outside, because your friend is right, he could get stolen/sunburned, and being a short muzzled breed could have problems cooling himself off when getting too hot. It's really sad that a lot of people don't think of what to do with their puppies once they get them home, and these are the pups that usually end up at shelters because people just look at a cute puppy and that's the deciding factor on bringing it home.