Locke presents paternal power, based on the assumption that young people have not yet fully developed their reason, to underline his belief that grown reasoning adults should become their own masters. Political power cannot be paternal because it either assumes that people do not have reason, or recognizes their reason and thus becomes powerless.
A similar description applies to the conjugal power situations Locke describes. They cannot serve as models for civil society because they are based on one of two relationships--master/slave or parent/child. Both are poor models for civil society: Locke has defined slavery as an extension of the state of war, and the parental model we have already discredited as invalid.
Locke's discussion of absolute monarchy logically extends from this discussion and becomes quite significant. First, it is significant because he presents to us for the first time a more detailed model for the correct way to go about establishing a civil society. Remember Locke's context here: Locke affiliated with the Whigs, a group of aristocrats with a mix of idealistic and practical concerns. He challenged the idea of an absolute monarchy on the basis that leaving the absolute monarch free to take the property or life of any member of society without redress violated natural rights.