Okay I would give money as well but I also can't help myself
Being the science girl that I am the reason for the weight restriction is Inertia a larger object or person is harder to stop.[
http://jvcscienceisfun.pbworks.com/w/page/12093323/GAK-Stubborn-Coin-Teacher-Tips
I am close to the weight limit and have done zip lines in Alaska and was told that the reason for the weight limit was because of needing to safely stop at the end of the line. That fits with inertia being the issue because inertia is directly related to weight. So that is my science fact for the day, sorry if I am being a bit Hermione about it.