PHP-5.3.0 is not a trivial update. Existing applications will require modification in order not to break when used with it.
I am certain that Alex is aware of this and is exercising caution in doing any update which could have far-reaching consequences for users.
I know from experience, with the ports I maintain, that some users always want the latest version but often overlook the quality status or incompatibilities introduced of these newer versions. As port maintainers we often have to consider the big picture.