Assuming the definition of compensation in the plan corresponds to W-2 wages for the spouse, I do not believe there would be any reduction because the self-employment tax does not apply.
They very well might, but, in my opinion, it is even more likely that they would get angry/annoyed at the possible results of their inaction.
Sometimes I wonder.
JeffC:
My perception is that you may be trying to overthink these questions and making them more difficult than they are intended. I would suggest that you follow SuePerry's recommendation that the answers are found in the text and try to avoid bringing in thoughts or logic from outside of the prepared materials.
I believe that you are referring to Lines 4a, b and c, which technically report prior Sponsor, EIN and PN (but not plan name) "if the name and/or EIN of the plan sponsor has changed since the last return/report".
I'm not aware of a formal notification requirement to the DOL. I believe that the plan will be tracked by EIN and PN, so changing Line 1a of Form 5500 should not create a problem.
Of course, there are notice requirements with respect to participant communication and information.
I got a call about the very article Bird brings up. The client is convinced of an impending apocalypse and wants to "hide" all pension assets before they are confiscated.