I'd be in no hurry to do much of anything.  Wait and see how this plays out in the coming weeks.  I haven't found a report that explains the thinking behind this.  When it came to the $300 above-the-line charity limit for MFJ, it turned out that the "intent" of Congress was buried in a footnote in the CARES Act committee report rather than in the actual law.  There could easily be something like that for this as well that I just haven't seen yet.

Absent other evidence to the contrary, I would (with the client's permission) take an aggressive position for folks "on the bubble" and disclose my contrary position while pointing to the language written in the law, "without regard to this section".

As Bob mentioned, this could have far-reaching effects, well beyond just the simple x% income tax.