It's obviously hard to debate counterfactuals but I disagree. I think having a publicly successful alternative available made the impact of deiselgate much worse (for EV alternatives/better for the planet).

Just like Nuclear can get away with being "better than coal" but in the face of plummeting wind, solar and storage costs its drawbacks get looked at with new eyes.

Or in some parallel dimension where deiselgate led to trillions being wasted on hydrogen fuel celled vehicles which never replaced ICE.