I do agree with HK that it's not a universal attribute of giftedness or even empathy to suddenly feel unwilling to eat meat. My nephew, probably HG+ and *very* empathetic in most instances, is a perfect example. B and SIL got a shipment of live lobsters when DN was 5 or so. He spent the whole day watching them, naming them and calling them his pets. B and SIL were pretty worried about their dinner plans. But when it was time to prepare them they told DN what their plans were and his only response was "oooh- I love lobster tail!"

I do think, however, that it's not an unusual predicament for the highly sensitive. Personally, if either of my kids wanted to be vegetarian or vegan that'd be fine by me. I'm a big fan of the nutritarian diet- consisting mostly of vegetables, fruits, beans and seeds. Given their lack of allergies I know I could feed them balanced meals without any animal product.