"Setting aside questions over the objectivity of HRW"
There are few questions over that. They are one of the most widely respected organisations in the field. Second only to maybe Amnesty International.
"White phosphorus is not considered a chemical weapon and is not banned per se."
Absolutely correct. Presumably you are ignorant as to it's status? It is permitted for use in making smoke to hide troops. Deliberately firing WP at civilians or indiscriminately at populated area (including in this case schools and children) as was done by the Israelis in Gaza is a war crime though.
"the six cases documented...killed 12"
Right - so the six cases documented involved 12 death. Seems perfectly clear to me. Many more would have suffered horrific injuries if 12 died.
"Human Rights Watch researchers found 24 spent white phosphorus 155mm shells in civilian areas of Gaza, apparently in the places where they had fallen" "Why "apparently" ?"
Presumably because they were being objective and making it clear that they didn't actually see them fall. The origin is not in doubt though as they had American marking, and the Israelis (after the usual lies and denials) finally admitted firing WP after the evidence became overwhelming.
"the numbers dead in Gaza are very small in comparison.....so this does not even come close to being "similar genocidal activities". "
Oh the numbers might be smaller, but the genocidal activities are pretty similar in scope and horror. Imagine the agony of children dying due to chemical flesh burns at about 900 degrees centigrade from White Phosphorus...
"Even using dubious HRW figures".
There is little doubt that those figures are conservative.
"Why pick on Israel which is in a deadly conflict with those ideologically opposed to the very existence of Jews "
Because Israel has killed thousands who have nothing to do with that view. Including a very high percentage of women and children. In the recent invasion, The UN says at least 2,104 Palestinian died, including 1,462 civilians, of whom 495 were children and 253 women. Versus the Israeli casualties which were overwhelmingly military - 58 Soldiers and only 7 civilians. The reason for this was a deliberate shoot to kill policy by the Israelis against civilians - again a war crime. See http://rt.com/news/255453-israeli-soldiers-gaza-war/