By enforcing a ban, does this mean that Yahoo! answeres has violated my rights?


No! If near were no laws or bans, the world would be more anarchic than it already is. You have rights, but the rights you have come with duties. It is YOUR duty to not put others surrounded by harms way, respect others, and etc.

It is your duty, in this case, to not violate undeveloped terms, such as cursing, inappropriate behavior, etc.
they have every right to ban you because its their site, for doesn`t matter what reason If you had any rights on Y!A (which you don't) you signed them away when you agreed to the terms of service.
What rights? THis is a privatly owned website run with T/S not a constitution.

Did someone promise you "Life, Liberty and the pursuit of Yahoo? "
Why? When you joined you agreed to a lingo of service. They probably acted in accordance with that agreement. Ban on what? What rights?

If you have be booted off YA for violations of the TOS, you have no rights. Private website, free to the public = they get hold of to make all the rules,.