That's not true. My cousin's husband, an NYPD cop, publicly shot himself in July of 1950 on the same day that another NYPD cop killed himself. Both officers were buried in Catholic cemeteries preceded by Requiem Masses. I have the newspaper clippings. Perhaps something changed with the 1917 Canon Law.
I tried to find the exact wording of the the 1917 Canon Law, but could not find it. However, it always described as more strict than the 1983 version.
Was this a private mass? It may be that this was allowed if done privately to avoid scandal. I highly doubt it was handled the way the Novus Ordo sect handles "masses" of those who commit ѕυιcιdє. The New Catechism doesn't even mention sin nor the deprivation of mass/ecclesiastical burial.