What's wrong with that? Well, for one thing, one man's terrorist is another's freedom fighter. In the day when U.S. administrations considered South African apartheid an acceptable evil and when Chile's Pinochet dictatorship was a strong U.S. ally, groups using violent means against those governments could have been labeled terrorists. These particular cases involved people who had given human rights advice to Kurdish rebel groups, and the Kurds are clearly an oppressed people deserving a homeland. The last time that I researched this, I found that the law also brands as terrorist collaborators people who give any kind of support, even a glass of water or a night's lodging, to anyone who has risen up in arms against a government recognized by the US - no matter how criminal that other government. So, anybody who helps the armed groups resisting the oppressive government of Burma, which renamed the country Myanmar, are also branded by this law.
What's the connection to Colombia? Large parts of Colombia's territory are controlled by armed groups like the FARC, ELN and Paramilitaries, which are very justifiably classified as terrorists by the U.S. And many of the innocent civilians who live in those areas are forced under threats to help those groups by washing their clothes, repairing things, providing food and lodging...anything. Thus, millions of poor Colombians are considered guerrilla collaborators and banned from the United States.
It's a very unjust situation.