i would think that it might be neccessary to permit posting in this thread during a suspension.
A suspended member can send an email to an admin, asking that it be posted on their behalf. Several of the admins make their email address accessible.
Of course, the admin would use his/her judgement on whether to post the email content. But if it is a reasoned argument and not an inflammatory reaction, it would likely be posted.
Note: I am not opposed to your idea of allowing suspended members to post in this thread, but that would probably require changes to the site software, so might not be easy to implement.