I'm a rookie to all of this as I've only had my EB for a couple of months, but... I've done a lot of Google-ing and ChatGPTing on this topic for other reasons. ChatGPT will tell you that those hard top posts are there to keep the tail light posts on either side of your tailgate from spreading apart over time when the hard top is on. However, it also says that a family rollcage that is bolted to six points (two points in the front passenger area, 4 points in the rear and cargo area) will prevent the body from twisting which is what leads to the tail light post spreading. I can't verify the engineering on that, but that's what our eventual AI overlords say.
One other point, which I haven't verified (but seems accurate ) is that the screws that hold the liftgate hydraulics in place go through the hard top sheet metal and into the hard top posts. I think some folks end up leaving the posts in the hard top and cut the bottoms off for that reason. I'll be installing a hoist in the next few months to get my top off for the first time, thus my general interest in this topic. Good luck!