[Kirk Y]

Instead of:

if condition="is_member_of($bbuserinfo, 6)">

<else />
$post[posts]
</if>

Use this:

<if condition="!is_member_of($bbuserinfo, 6)">
$post[posts]
</if>

You also need to edit the relevant templates that display the post count elsewhere on the forum, e.g.: MEMBERINFO, memberlist, etc.