I can only think of a few problems that might result from reloading on a carpet.
If you drop any primers, they may be hard to find depending on the type of rug. However, do not try to find them with a vaccuum cleaner.
If your carpet does cause noticable static, you're going to have a problem with electronic scales if you use one. Static seems to make them go crazy as you approach the pan if there is a static buildup on your body. Also, static can cause powder to tend to stick to scoops, funnels, the side of powder measures, etc. A humidifier in the room should help quite a bit.
Unless you spill a lot, some spilled powder shouldn't be a problem.