I dunno, shouldn't moralistic self-identified "conservatives" be a little nicer, considering that they claim to have access to the one absolutely correct moral code? Shouldn't they come across as a little more fulfilled by their own lifestyle (it is the One True Way To Live Correctly, after all, shouldn't it be more positive and attractive?), and a little less grouchy-grampa angry old white man yearning for the good ol' days when blacks and wimmins couldn't vote and everyone was Christian and nobody could get enough money or power to dispute the white male conservative mindset?
That brings up the issue of what you mean by "nice," though; I try to be "nice" in the sense that I try to refrain from calling names or just blatant character assassination, but I don't think that necessarily equates to being nice in the sense of not wanting to offend or hurt anyone's feelings. If you genuinely believe that what someone is doing is morally or ethically wrong, then it seems consistent that you would value your position in that case above that person's feelings. For example, if you think that someone trying to block blacks and/or women from voting is making a hugely immoral dick move, then I don't see any reason why you would prioritize not hurting that person's feelings over actually doing something to stop them --- if I had a choice between solving a problem and not pissing someone off, I'd solve the problem every time.
For all the things that I never did
For all the places I never was
For all the people I never stopped
But there was nothing I could do..."