All we know is that Apple was bankrolling a portion of OpenGL development on OSX and now they feel otherwise. OpenGL ARB is a committee and Apple has only one vote. Maybe they were not satisfied with the direction the spec was going. Its certainly not an unfounded belief.

>I don't see how a technology can get to a mature status if a major hardware company decides to not support it.

Alternate reading - They gave it their time and money, and it didn't work out.