And the legitimacy the Saudis claim comes through the request of help from the deposed president is at least invalid claim because, as I mentioned earlier, his presidency was established through a "presidential election" in Yemen "on 21 February 2012" were he as "Acting President Abd Rabbuh Mansur al-Hadi was the only candidate in the election. He was sworn in as president of Yemen on 25 February 2012 in the Presidential Palace...Hadi won 99.8 percent of the vote".

So he himself  can hardly be seen as truly elected president and therefore has no legitimacy especially against others from the same country.
[(Added 9/03/15: Although content of the quote above can be found in the links mentioned there, HERE is where the the quoted text can be found ]