I never block off the kitchen at home, so I wouldn't think anything of it if I went somewhere without the kitchen blocked off. We have locks on all our cabinets, the oven has a lock, and all the doors (pantry and laundry room) are shut...I don't see anything dangerous about that at all!
IMO if the child wanders off, it's the mom's job to go retrieve him and make sure he's not putting himself in danger. You've baby-proofed, but the mom's still need to do their job.