I am pro free speech and I can´t really understand why we can´t talk about possible IAs in public.

If ppl want to argue about things, let them. Sometimes it is even interestning and amusing.

Sometimes there are ppl who break the rules and mods can get information they need from these arguments.

Mods do not need to read all of these accusation threads and try to find proof from them. It is just extra materiel for them if they wish to use it. IRC would still be the official channel to report wrongdoings.