Many had homes and families in the USA. One was apparently a US citizen. They had no desire to be moved to Martha's Vineyard, which would make it impossible to get to their court date. They had no desires to suffer to be your political pawns.
They were told that they had to go to Boston, or be deported. That was a lie. When you see people acting against their self interest, that is clue they are being lied to.
Back with their families, waiting for a court date. Remember these were the easy cases. They had families in the area.
They were welcome, but there is no courthouse on Martha's Vineyard. Building a courthouse for 50 people makes no sense. They had to be moved to where there is a courthouse. And given they were taken from their families, they wanted to get back to their families.