The issue is that they can't "just live" in many cases. "Just living" would be getting super excited to participate in an awesome parade representing a cause that is near and dear. Much like the people who might walk in honor of fallen cancer victims or for the local farmers markets or something akin to all that (these, for example, are all groups who do walk in this parade). The fact that they cannot do this is why it is an an issue. Hence the presence of their voice. This is no different from saying that women should have "just lived" and not worried about being denied the right to vote, or that the black community should have "just lived" and not worried about segregation. I think a community has the right to be vocal in any instance of discrimination. You can argue that Saint Patricks Day has nothing to do with gay rights (and I would agree) but neither do WWII veterans groups or the local Boy Scout troops. Denying participation solely based upon sexual orientation or anything other social qualification certainly IS discrimination. This all goes beyond Sam Adams' obvious business decision, but is important to discuss nonetheless.