The marriage is the traditionally sanctioned ritual of family commitment; I thought this would be common knowledge on a purportedly conservative website.
Being unable to make that commitment with a child already born indicates strongly that that commitment just isn’t there, although Bristol may hold out hope than one day he’ll be up to it (or not, again, I don’t assume that the father is the one preventing this).
I get the feeling you are one of those 'right wingers' SNL proofed when said Sarah was 'forcing' two unwilling teens to get married. Marriage is a huge decision. Let them take their time.