Argueably, I'm probably the best example of a lengthy forum suspension, ever, and therefore, again argueably, the best to offer this position.
If you transgress in the general fora and receive a suspension ( the merits for or against is not the issue here ) there could be a perception that there is no real penalty if you were then allowed to retreat to the sanctity of your private clan / club forums and so to continue the debate and / or perceived infractions, supposedly indifferent to and beyond the powers of the very people who originally determined that there was a valid reason for that suspension.
No penalty there, not one that has any impact as far as I'm concerned.
I didn't much miss the ability to post in the general fora - they're pretty much rubbish these days - what really hurt was the inability to post in my nominated clans and club private forums. That's the sting, and that, and that alone, needs to be in place to convey to those members who choose to breach the TOS with regard to forum posting, that that's the bottom line.
Change nothing. It's working.
I know that for a fact.