They discovered that some of the workers were involved in the terrorist attacks that killed over a thousand Israelis (most of whom were innocent civilians).
It's good that they are willing to revise their stance in the face of new evidence.
Sadly we'll never know how many of those civilians were killed by Israeli attack helicopters and tanks firing on their own people. Wouldn't surprise me if it was at least half of them. In which case maybe the US can also stop funding Israel and the conflict will soon come to an end as the region finds a new balance.
It's good that they are willing to revise their stance in the face of new evidence.