Let's pick the frame above apart like @
Pine Cone has done, and see what I have to get them to put in.
The bottle cage nuts won't interfere if a derailer bracket is welded on. If a bottle cage was installed, the seatpost will indeed not be able to be pushed down, but that is not needed on the Swift. Also the bottle cage would bump the top tube when folded, preventing a full fold, but I don't think that is a massive problem. I think it's a bigger problem that road grime will splash on the bottle in the wet.
is it possible not to have the bottle cage bosses in the seat tube as presented? there is just so much grime and dirt that hits that area. i would prefer them in the original position (handlepost) or on the top tube (similar to the tyrell fx).