No, it's not. You have no idea what you're talking about if you think it is.
Ever watched any of those court shows on TV? Ever seen any of those silly surprises and objections where the judge then looks grave and says he/she will allow something or not? Here's a clue—when they say they won't allow it, that's not a violation of the 6th Amendment.
You get to bring information and witnesses relevant to the charge or issue under litigation. All courts have the responsibility to decide what information is relevant. They disallow irrelevant information and witnesses. Everyone who gets portions of their case disallowed feels annoyed, but that's too bad, and it isn't a violation of the 6th Amendment. It's the way legal processes work.
If you think it's a violation of the 6th Amendment, take it up with Lakin’s current counsel. He doesn't. But then, he does have the advantage of knowing what he's talking about.
What WOULD be a violation of the 6th Amendment? Give an example.