After skimming, I find Judge Reo’s dissent reasonable: the House needs to invoke its impeachment powers for such a subpoena, not the legislative pretext.
It’s a warning that the House could lose 5-4.
2. The full opinion linked here.
3. The easy solution is for the House (or committees, but arguably should be full House) to take a formal vote to start impeachment inquiry and re-issue subpoena w/o leg pretext. Problem solved.