They only associate with other orthodox Jews. And if you believe that, does it make you an anti-semite?
If an orthodox Jew only associates with a certain sub sect of Jews then they're being segregationists.
I don't think expressing that opinion makes one anti-semitic.
But are all orthodox Jews really like that? Nope. I happen to be friends with one, and he has many non Jewish friends. His father also has many non Jewish friends. I even got some amazing business hook ups through his family.
See what I mean about making broad statements about a group of people rather than engaging them as individuals?