I think it's always been this way, including at every past convention. They've always been on Saturdays and it always is detrimental to observant Jews, people who work on weekends, military reservists, people who are out of the state, or people who just have lives and don't want to go to some godforsaken basketball arena in Roanoke or something. That's how conventions work.
When are they supposed to have their convention though, on Sunday or on a week day?
I mean ideally, they could have a primary with polling stations near to the voters, but that would make it far too easy to vote. But yeah, I agree Saturday would be a better day than any other.