Buyers can only be left positive feedback or no feedback at all, it has been that way since 2008

If you leave a green tick with a neg comment (aka, a 'false positive') your account will be pinged again, as this is a violation of policy

Plus no point since nobody else knows who the buyer is anyway as nobody outside the transaction see the buyer ID

It isn't making anything harder for her, she does not have to do a thing now that she has opened the dispute

It is pretty much 'cutting off your nose to spite your face'

The buyer is not the one who will get 'punished' (for want of a better word) by eBay