ABA adopts amendment to Model Rule 8.4; is it unconstitutional?

Back in January I wrote a long post on a proposal to amend Model Rule 8.4 to make it a sanctionable offense to engage in harassment or discrimination.  I thought that the original proposal was problematic for a number of reasons.  Some of the problems I thought of originally were addressed (and fixed) in subsequent versions of the proposal, but I still have some concerns.  The final version of the amendment is available here.

Here is my concern: the adopted amendment does not address the fact that the new rule can be applied to impose sanctions on attorneys for expressing Constitutionally protected speech.  In fact, on this point, the adopted proposal is worse than the original.   The earlier version of the proposal stated explicitly in the proposed new comment that the rule did not apply to conduct protected by the First Amendment.  Unless I missed it, that language has been taken out. 

Worse still, the adopted comment to the rule states that the rule applies to "harmful verbal . . . conduct that manifests bias or prejudice towards others."

What exactly does "harmful verbal conduct" mean?  I don't know how that is different than a verbal expression.  And once we understand that as an expression, the First Amendment's protection of freedom of speech comes into play.

And what is it that makes the expression "harmful"?  As stated in the new comment, it seems that what makes the "verbal conduct" harmful is the fact that it "manifests bias or prejudice."  Note that it does not say verbal conduct that results in some sort of exclusion or discrimination.  It only seems to require that the verbal conduct express bias.

The ABA being a private organization can adopt any rules it wants to apply to its members.  However, assume a state adopts the new language for its own rules, how would that not be an example of the state trying to penalize someone for expressing his or her views because those views are objectionable to others?  Isn't that what the First Amendment is there to prevent?

What do you think?  Can a ban on "harmful verbal conduct" survive a Constitutional attack?