Do you think Granger's comparison of humanity of the phoenix adds to a major theme of the novel? Explain you answer.

I think that you can argue that it does.  I think that one
of the major themes in the novel is the idea that a society like the one Montag is
living in must be destroyed pretty completely before a new one can be
made.

We see this in some of the things that Faber says to
Montag.  He tells him that the goal should be simply to hold on until something happens
and they can start the society again.  Maybe if that happens they will do a better job
the next time.

So we have this idea that the society needs
to burn like the phoenix so it can rise again from the ashes.