I think any normal game they wouldn't have but with three hours of pre-game festivities, a daytime start, a sold-out crowd and Friday already open, it was easier to just call it. If they'd opened the ballpark it would have wound up being in the umpire's hands rather than the team and MLB. Gotta be a big inconvenience for some but an opportunity for others.
One assumes the forecast is also pretty solid. Not that they might not be able to play, but they don't want to play with delays. Better for Wheeler and an extra off-day for our bullpen too.