So, the effort to get buy-in from the big companies that matter has been going on for some time, and now that we've done that, here's the result: Every big company that matters except Apple.
It's not as though the list of the four big companies that matter is too long to reasonably be expected to name the fourth, and the name of the fourth is not webkit.org or Fil Pizlo.
So, it seems to be either an "Oops, we accidentally left one of the four out of this important announcement," or there is still enough of a problem with Apple that we decided not to delay the announcement any longer to wait for them.