Why am I not surprised it was a low feedback buyer? They always seem to go for the jugular, without trying to resolve with the seller first. I had a look at the listing and I am assuming the "included" is what comes in the box and the "minimum required" is the other things you need to buy to make it fly?

I looked at model aircraft for my husband a few years ago and each one in the shop was just the kit to build the actual plane. The motor and everything else was extra. It clearly stated on the boxes that the motor and other bits weren't included. 

If everything is clearly stated in your listing, it might be worth RINGING eBay and talking to a supervisor about getting the feedback removed. With any luck they will remove it and fix your stars up too, which I'm assuming that buyer also trashed. If they say they can't do anything, don't give up, call back (or get a supervisor to call you back, apparently you get someone with half a brain when they call you back) and try again. Sometimes it can take a few calls.

Maybe to avoid any confusion with other potential numpty buyers, change the minimum required" to "extras you need to make this fly" (or something to that effect). Then there is absolutely no confusion.