I would not say restrict them from commenting but rather make their first fee post rather critical.

Kind of like a karma multiplier so you get an instant separation of quality and then you can look at penalizing those that take the down delta rather quickly.

Choosing to assume someone is guilty before they commit an offense would surly drive bright people away.

Anyway good comment and don't get to intimidated, many of us are just wind bags anyway, bright sure but wind bags none the less.