if you genuinely can't trust the mods not to protect a friend as nasty as this from consequences, to the point of closing their eyes to harassment, to me that's definitely cause to drop.
but if you want a slightly more optimistic approach, i would see about arranging for multiple reports from a mix of sources, ideally none of whom are yourself directly. safety in numbers, plus harder to ignore multiple concerned parties.
Re: -1
if you genuinely can't trust the mods not to protect a friend as nasty as this from consequences, to the point of closing their eyes to harassment, to me that's definitely cause to drop.
but if you want a slightly more optimistic approach, i would see about arranging for multiple reports from a mix of sources, ideally none of whom are yourself directly. safety in numbers, plus harder to ignore multiple concerned parties.