"Neil, sometimes I question your wisdom. Pretty much EVERY roll cage out there is "pre-buckeled". So, what you are trying to say is the fabricator " pre-buckeled " it so, in a accident, it isn't efficient in saving lives."
Brian, it is wise to be skeptical but you should find out about whether it is correct or not. True, most roll cages are fabricated with bent tube members. That's not to say that the practice is optimum. In compression, a straight tube is stronger than a bent tube. That is not debatable but you can make up for the lack of columnar strength by making the tubing larger and with a heavier wall. Not as structurally efficient but it works. If it were not for minimum tubing size requirements in various sanctioning organizations most chassis & roll cage could be lighter and equally strong if fabricated with all straight tube members.
Ken, in the last photo it looks as if there are some spacer washers missing between the inside of the bracket and the rod end ball.