Well, if I understand things correctly, the LPC Noob is half correct. The courts will probably rule, when the case finally gets there and goes through the chain of courts, that the House cannot get the tax returns unless it is for some aspect of proper House proceedings. The current fishing expedition would not qualify; impeachment proceedings might. OTOH, I do not think the courts could force the bypass of rules about grand jury material, nor, I think, essentially declassify redacted classified material.
Realistically speaking, it's April, 2019. The election is less than 19 months away. The chances of anything happening that DU-grade Proggies will like (initially) are fairly low. IOW, the prospects are cloudy, with a high likelihood of Whomp-Whomp.