Rear canopy posts on aftermarket rear seat. 2006 Precedent

[Gazoo]

So my recently purchased 2006 Precedent came with a relatively new aftermarket rear seat/fold open pickup bed. As I slowly disassemble everything to give it a once over and clean off the years of neglect I noticed the rear canopy post/drain-pipes were replaced with a hollow square channel just like the front (likely part of the aftermarket kit?) - but they just kinda sits in the rear holes without anything but gravity holding them down. I guess the original posts were plastic and form-fit snugly in these holes? My worry is that over time the vibration will make these posts chew a hole threw the plastic. Maybe the previous owner neglected to put a piece in those holes to better receive the square channel? Other than that it does appear to be a pretty robust install.