I wouldn't go so far to say I'm particularly a fan (would I buy her CD? probably not) but I've really enjoyed Zayra thus far. I haven't heard her own material but I suspect she may have some fairly interesting stuff. She really is great onstage and obviously, since she is a recording artist in her own country, likely has enough of a fan base that is voting for her. I don't think it's a VFTW situation at all.
BTW, I don't think Toby is untouchable at all. He's had a turn in the bottom 3 and SN doesn't seem THAT enamoured of him. Once you discount the Zayra factor (if you believe she is inevitably on the chopping block), Toby's position is precarious - he's at least a distant third to Lukas & Magni.