I think the 'Flag As Spammer' feature is a little dangerous for forums as moderators could easily flag any member as spammer. Even those with lots of posts (for example 1000).
And I'm sure many people have configured this feature so it will automatically delete all of the users posts and empty their profile.
My suggestion: Give us a setting in the ACP where we can specify the maximum amount of posts a user may have in order to make the 'Flag as spammer' option available for them.
On another note: I would love to see a soft-delete option for the "Action to take when a member is flagged for spamming" checkbox instead of the current hard-delete option.