It's complicated.
Certainly many non-Jewish Poles were complicit, at the very least. In the years prior to the Nazi invasion, there was lots of antisemitic propaganda, hate-speech, threats and violence toward Jews by a large segment of the polish people, with little to no effort by the Polish government to quell it. Much of it was fueled by the Catholic Church, which surprises no one since the Church was highly complicit in the holocaust overall as it has been in countless other acts of genocide and ethnic violence.
This laid the groundwork, and made the work of the Nazi's far easier, and strongly implies that many Poles were not really being coerced to help, even if they were "following orders." A number of Poles also blackmailed Jews under threat of turning them in.
However, the Polish leadership did not form formal alliances with the Nazis and there was no Polish SS unit, unlike other occupied countries. Also, there is evidence that millions of non-Jewish Poles risked a lot, even their lives, to help the Jews. And almost 3 million non-Jewish Poles were killed by the Nazis.
So, the comments by Katz were wrong because they were a blanket unqualified statement about "Poles". OTOH, holocaust enabling antisemitism was a deep rooted and widespread part of Polish culture before the Nazis and remains so today.
Recent studies suggest that somewhere between a third to a half of Polish people hold dehumanizing and/or otherwise Antisemitic beliefs about Jews.
(Note that only some of the measures in the linked paper can be interpreted as "anti-Semitic". Some measures merely assess whether people think that there are Jews who are biased in favor of Jews and seek out economic and political alliances with other Jews.)