On the other hand, I also strongly believe in people's right to hold other points of view. I would certainly want no truck, as an individual or as a customer of a business, with someone who made a habit of expressing the differing opinion in hateful terms or by actions designed to injure the subjects of that opinion (eg firing gay employees or refusing to grant benefits to same-sex spouses or domestic partners), but on the other hand I don't really have a problem with someone who treats everyone consistently and with respect, although that person might have quite different beliefs from me about how things should be.
The thing is, there might be a wide range of things motivating that belief, from some deep pragmatic, religious, or moral conviction to simple antipathy. Unless the person acts or speaks to signal what those motivations are, I don't see any point in trying to make judgments about them or by extension of the person, for the same reason I wouldn't want people making extrapolations about my character from a single data point. This hasn't stopped a lot of other people from demonizing Eich on the basis of his donation, without giving any apparent weight to his behavior at Mozilla or the experience of LGBT people who work with him there (several of whom have blogged in support of his appointment notwithstanding their disagreement with his support of prop 8). Not being gay it's easy for me not to take the issue personally, but I'm inclined to give a lot of weight to people who are gay and deal with him on a regular basis.
The whole business has an unsavory air of internet bullying to it, to be frank. I'm not thinking of people like Catlin Hampton who went public about their discomfort with Eich's appointment so much as the large number of tweets, comments and so on that adopted a confrontational stance and made it into a zero-sum binary issue, eg people calling him 'Eich(mann)' and equating him with the late and largely unlamented Fred Phelps. Characterizations of this sort don't seem any better to me than characterizations of gay people as perverts or suchlike. Bandwagon behavior seems to bring out the worst in people and reminds me of why I generally dislike being in groups.