I just looked it up and I imagine it's just that it's an old-style steel post in an aluminum frame. That style of post can be fine, but I find that the cheap(er) ones wear out when they've been adjusted a few times and the seat will no longer hold position well. Also (you might already know this), since these kinds of bikes often don't come with their bearings lubricated, I'm sure the posts aren't either. I would probably replace the post with an aluminum micro adjust and put some grease on it before inserting it, but you could just grease the steel one to reduce electrolytic corrosion and maybe remove it every year or so and re-grease it to make sure it doesn't weld itself in. If you do this and get your seat angle adjustment right and keep the seat clamp tight, I would think you'd be fine unless there's a specific peculiarity to this bike. Even then, though, you can replace the clamp independent of the post if that part's a problem (unless it's some really weird size).