knows halachas better than Rav Pam or Rav Yaakov Kaminetsky
Even assuming the stories were true, which is an assumption, it could well be they weren’t aware of the origins or history of All Hollows Day and Halloween. They never issued a psak on this and we don’t pasken from stories. When Rav Elyashev paskened sheitels are assur due to A”Z, many argued against that saying Rav Elyashev wasn’t familiar with the actual history of how the original hair was compiled. Does your family use sheitels that contain human hair?
Have you considered the fact that Reb Moshe didn’t hand out candies on Halloween? And that Rav Aharon didn’t either? Nor did the Satmar Rebbe, Rav Gifter, Rav Hutner, Rav Ruderman, Rav Schorr, Rav Birnbaum or Rav Svei. And today candies aren’t distributed on Halloween from the homes of the Novominsker Rebbe, Rav Dovid Feinstein, Rav Shmuel or Rav Aharon Schechter.
So if one is to pasken based on anecdotes, then we can pasken from the vast majority of Gedolei Yisroel who did not, and do not, partake in Halloween in this manner that we may not do so.