This was a federal trial on a federal charge. The judge could have easily admitted the guy's lawyer of choice just for that particular trial, but chose not to, for whatever reason. Instead the case was handled by a proxy, who had never tried a federal criminal case before in his life.
It is called "pro hac vice" (pro hak vee-cheh)
It allows a lawyer to appear for a particular case as long as there is a local counsel to vouch for them. This is how you have these national lawyers appearing in all the various state courts.
VERY routine. Only becomes an issue if the lawyer is doing it too much. Then the judge will say, go pass the state bar.
Of course this begs the licensing scheeme. Does this mean, that as long as you are a lawyer SOMEWHERE you have to be permitted into a federal court?
(BTW you don't have to be a lawyer to represent people in the immigration service)