I think your worry will be that the "pod" with the arm needs to be extremely strongly mounted, probably welded or use one continuous piece of material through the robot for strength. If it has to be removable it will more than likely mean bolts, which will have to take a load of force going through them. At this point its raw maths as to whether the bolts you plan to use will take the forces involved before sheering. If the maths looked good I'd have a crack, but if it looks questionable I would say you need to focus on a complete frame dedicated to crushing.