Giving this a nudge to the Q&A board, since that would be a better fit about a general question about treating moopy rope.
My first recommendation would be to return it if you can. Even if there's a small restocking fee, consider it the price of a lesson learned (get a small quantity to test on any material you're going to use before making a bulk buy). Any money you saved on that will likely get eaten up on treatments or coatings. There are loads of non-MOOPy ropes out there, and you may even be able to get some really big braid stuff to give it a nice oversized look that might work well with an oversized/human-sized tower.
If returning it's not an option, and it's too expensive to just replace with better material anyways, I'd recommend looking at a clearcoat/polycoat. Brushes on wet like paint and has a milky color, then dries hard and clear. You can even get stuff that's water-based, so you can clean up with soap and water instead of having to use solvents. The downside is that it's something you don't want to apply on-playa - if dust kicked up while it was drying, it's be stuck there forever and it'd look more like litterbox clumps than a rope scratching post. Most hardware stores have a wide selection of polycoat, MinWax is a popular brand. You can get a little quart-sized can for under $20 to test with before committing to gallon sized cans for the bulk of the project if you go that route. Good luck!