Asking his resignation for something that has strictly nothing to do with the job he has been chosen for is not right. The fact that Mozilla's community is asking it doesn't change that. Members of this community base their opinion only on their own ethical and/or political point of view, which makes the general opinion completely biased. Asking his resignation because of his ethical/political views makes as much sense as asking it for religious reason: people get angry about it, and most of them can't even argue about it properly (I'm saying this for all sides). There is a board for a reason: to make rational decisions based on the work they think he'll be able to do. And it seems like they think than a donation made 6 years ago didn't alter his ability to do this job...
But if you really want to boycott him, you should not block Firefox browsers from visiting your site, as it's more the product of a community than a single man, but you should stop using on it the language he created (Javascript).