You can bet if they asked for Biden, Pelosi, Shumer, Kerry's or even Mitt's tax records showing graft and kick backs from enemy countries the Supreme Kangaroo Court would say there was no 'standing' to waste their time.
I know we had a moment of agreement elsewhere, but I am not sure this is looking at the problem from the right angle. First, and only semi related, I don't think anybody's taxes should be used against them in witch hunts, political or otherwise, and I think that is exactly what this is. From what I can tell, and I have been in the investment business my entire career, Trump's taxes, from what I have gleaned from leaks, look just like anybody else who invested mainly in real estate. I think RE investment accounting is basically unfair and sleazy, but what he seems to have done is not illegal.
Okay, so the second part is that while you may be right about the above players, Trump's argument was that as President he was totally immune from this. I think that is bullshit, and while I almost always agree with both Alito and Powell, I think they were wrong here. But now he is not President, so their argument is moot. They didn't really have a choice but to acquiesce to this. In all fairness, there is no reason that, if my taxes are fair game, the President's shouldn't be. These aren't acts made by the executive, but by a private individual.
But, I think the real issue is that Republicans have never used lawfare against Democrats like Democrats have against Republicans. It is a relatively new phenomenon, and it goes back to the Wisconsin John Doe investigations. Kim Strassel wrote a great book on these, and it is a good roadmap for understanding lawfare in general. Arguably, the whole Lois Lerner scandal would fall under this as well, though it is slightly removed.