I'd say there is an argument to be made behind the motives for this. The fact that they threw in the laughable "Voting Rights Act" excuse shows they have something to hide. I'm just curious whether it's a matter of federal funds or setting up a future case where they can be allowed to draw maps by eligible citizen voters, which would give them another advantage in redistricting, or both. To think that Republican actions here are innocent is incredibly naive. They are leveraging their power at the federal level to help them win future elections, just like they have done in the past.
I'm not sure that the VRA part is an "excuse" on the part of the Census Bureau. I know from panel discussions going back to 2009 that this question of citizenship has been one they have wrestled with long before this administration. At one 2010 meeting expert redistricting lawyers were giving their best ideas for workarounds to try to be compliant with results from the prior decade's cases.
As recently as the 2000 Census, 1 out of every 6 households was sent the long form that included the same citizenship question in the 2020 draft. Cases were using VAP in the 1990's cycle, though for Latinos it was recognized that numbers well above 50% were needed (The 7th circuit went along with a threshold just under 60% for IL-4.) Courts weren't requiring it, and the long form needed to be moved out of the decennial Census, so the question was dropped for 2010.
After 2000 courts leaned move heavily on CVAP, and not just VAP, because then all groups could be treated by the same use of the Gingles test when identifying that a minority made up 50% of a compact area. However, realization of the impact of those decisions on mapmakers came too late to affect the official list of questions. The courts have continued to move more in the direction of CVAP for the VRA, so shouldn't the correct data be available at the time the plan is prepared?
And yes, I get that there are partisans who would think this will help them in future elections. But I don't see how that changes the underlying issue. We should also be able to look back to the 2000 Census and see how the response rate for the citizenship question on the long form compares to the ACS. If there are real differences, then yes I would agree that more work needs to be done to improve education and outreach on the question. But if not, I think those who are fighting this may be just as partisan as those who are motivated to add it in hopes of winning future elections.