The information we have about both historic cases is second-hand. On top of that, history is written by the victors and there is a good amount of nuance lost over time, as your example of Father Coughlin demonstrates: barely anyone knows today that there was factions in the US supporting Germany, and that's mostly because it didn't fit the narrative that the US wanted to establish in the history books.

Secondly, we cannot epistemologically know if deplatforming Coughlin or the Hutu radio saved lives. It's even possible that shutting down the Hutu radio could have inadvertently silenced moderate Hutu voices that might have offered alternative perspectives or advocated for peace that could have changed the dynamics of the genocide.

My point is it is impossible to attribute positive consequences to the restriction of speech, but the negative consequences of restriction of speech are always self-evident.