I'm not saying he's blameless.
Sure, but everyone with considerable political power and influence need to be part of the inquiry so as to know who exactly caused what. Earlier on especially, though after the danger of spread was understood, there were events that were allowed and weren't shut down, some attended by high ranking politicians. On the flip side, some politicians pushed for masks earlier on while others didn't. We need to know who was responsible for what at the end of the day, and what could have perhaps been better or worse decisions made by them instead. The public should be able to take that individual info and decide who's more influential and how much that matters to them.
I don't object to any of that. If there's reason to suspect anyone in a position of power did anything less than follow their best judgment, with the goal of protecting lives, they should be held accountable. As the President, Trump should be the first to be scrutinized.