These guys figured (probably correctly) that this woman was a radical left wing hater of Israel, who'd come to make trouble, and they didn't want her to feel too welcome. That doesn't justify it. The main damage is to Israel's reputation, when things like this get reported. Israelis tend to act with a high degree of independance and improvisation, and in these situations you need rules and regulations so these things don't happen.
We want Iran cooperation, not meddling, Gulf Arabs tell Kerry (Reuters)
from the article: Police shoot U.S. student's laptop upon entry to Israel