Yes, denying genocide is part of freedom of speech
Yes, those who deny past or ongoing genocides are exercising individual right to free speech as protected by the First Amendment. Expressing an idea that is contrary to those held by others is a good working definition of the ability for Americans to speak out without fear of persecution. As long as these words do not unfairly target or slander anyone, these ideas regarding genocide are fair and must be respected under Constitutional directives.
Yes those who deny genocide are still entitled to the protection of the First Amendment.
The constitutional protection of the Bill of Rights, including the First Amendment, apply equally to all US citizens. Those protections are not dependent on the nature or content of a person's speech. The courts have ruled that even unpopular speech is entitled to First Amendment protections. This is the American Way.
They deserve it.
While denying genocide might be an awful thing, people's rights should never be taken from them. Denying genocide doesn't hurt anyone directly, akin to if somebody were to yell fire in a crowded theater, so doing so doesn't infringe on the rights of others, so while it's a dumb thing, it's not illegal.
Yes, they do.
This is definitely the ugly side of free speech, but if speech is really going to be free, there isn't much you can forbid. And it's good, also, because it gives complete and total morons a platform on which they are happy to expose themselves to the world on. They, also, deserve the protection.
No, free speech is not about the right to lie.
As long as there is enough proof that genocide has existed, such as in the Holocaust, someone who denies it is blatantly lying. Our freedom to speak is freedom to speak the truth as we see it but not to deny facts or to stir up hate and fear among the people.