Protecting anyone hasn't historically been a concern for terrorists at all. Islamic terrorists, in particular, hit entirely Muslim targets all the time.
And no, even then, production and delivery isn't easy. There are no pathogens which are both highly infectious and highly pathogenic, both because those traits are mutually inhibiting, and such a pathogen would already have run its course in the world. Any attempt to increase infectiousness and pathogenic potential, however, would require a very large foot print, virtually guaranteeing discovery by law enforcement.
