It's a fine line and I can understand your concern, but Mr. Sheen has chosen to shove his political views in all our faces by abusing his special access to the media, access that you or I could never dream of having. Not to mention, he does it with his character's persona.
I happen to have very strong political views (why else would I be here?). However, I don't make a habit of making a big issue of my politics at work, and I surely don't parade them in front of clients. If I start hammering away at clients with political opinions and offend them to the point where they take their business elsewhere, I'm not going to keep my job very long, and there are probably very few people who would disagree with my company letting me go for chasing customers away like this.
This is exactly what Martin Sheen is doing - getting into his customers' faces and bellowing out loud that unless we agree with him, we're stupid, unenlightened, racist murderers. By using his President Bartlett character to promote his message, he's even using company resources to insult and bully the client. If this guy is going to cost his boss (NBC) money by driving away the business, I think NBC would be remiss if they DIDN'T let their concerns be known.
I don't have a problem with him embarrassing himself. I'm sure he honestly believes that most of the US little people agree with him. This comes from too much Hollywood inbreeding and their just having to be loved by everyone. The attention he is now getting no doubt is a big surprise and once the Iraqi people rejoice over their newfound freedoms, there will be a lot of explaining to do by this crowd.