I'm sure Sporting fans will come at me, but as a neutral (I've supported Académica all my life) I have to point out that this would've most likely happened if Sporting or Porto were in Benfica's place.
Although it was a bit different, last season Sporting declined to postpone a match against Vitória even though they had around 20 players sick or recovering from illness. They had to field a squad with reserves and couldn't even fill the bench. It was embarrassing at a the time but it has been forgotten, like this will be in a couple of months.
Our football is rotten in favor of the big 3, it has been for a long time, probably ever. Everything, and I mean everything, is designed in favor of the big 3 (they get waves in competitions, there are special rules where they can't face each other in the league cup effectively guaranteeing they can't face each other before the final 4, there are rules where they can't play each other in the beginning of the season, etc.).
And don't get me started on how the referees treat the big 3 and how they treat everyone else, books could be written about this.
I'll concede that lately Sporting gets more stick from the "football powers" then the other 2, but for non big 3 fans, it's absolutely hilarious seeing Sporting fans complain about Benfica or Porto, or vice-versa. Just because they are a little bit below Benfica/Porto in terms of power in football, they can't realize how benefited they are compared to everyone else in the league. It's both tragic and comedic.
Only someone who knows very little about how portuguese football works can be remotely surprised by what happened yesterday, and I'll say it again, if B-Sad was facing Porto or Sporting, the exact same thing would've most likely happened.
Now, my sportinguistas friends, I'm not up for a big and lengthy debate about this on a foreign forum where no one else will care, so don't expect it. I'm sure you will disagree but in a way, that's kinda my point. Big 3 fans live in an alternate reality when it comes to fairness in football.