I read this passage and disagree. Well, I don't disagree with the final point. It is true that nothing matters to the universe. There is no 'god' thing watching us all. Our universe, I am convinced, is one of zillions constantly popping into existence as the physics of dark energy and virtual quantum particles continue their work.
But contrary to the implied bleakness suggested by this Weinberg guy assertion that it's "pointless", this vast multiverse idea seems to me to give our lives even greater meaning. The infinite course of the multiverse might not care about us but we still exist. Our lives matter to us and to those around us.
That there is no grand external 'meaning' says to me, that our actions are the only thing that really do have meaning. It tells me that what we do is the only thing that is really important.
The reality we construct, our actions in our society and culture, our reliance and support for each other, are not pointless. With the realization that we are less than a speck in the grand reality where nothing is any more important than anything else, we become the most important thing in the universe.
All the rest is nothing, vast and empty. Only we are full of life and joy and love and hate and humor and meaning. As far as we can tell, that's all there is. That makes it infinitely more than pointless. It is everything.
It makes me think about those who say life can have no meaning without a god. In their view, their god has meaning. Our meaning is purely derivative, just as our liver cells are important to our getting an award. We just come along for the ride. Our liver cells didn't kill us by getting cancer and we didn't stop the god's glory by failing to worship it.
This reality of the universe says that our glory is not subsumed by anything else. No other meaning is greater than our own. Our meaning is all there is. For twenty thousand years, humans have been fabricating meaning from whole cloth. With luck, we will continue for twenty thousand more.
The multiverse might not care but we do and, apparently, that is everything.