Let me ask.... was the role a paid one?
Look I get how everyone is trying to save money. I am on a budget too. But if I have to make a decision about paying bills and doing something for free, can you guess my decision?
Yes, this is cold and impersonal, despite my own personal feelings, if I have to choose between a job that is going to pay me to help me make rent, and in another in a project that cannot pay me anything more than some pizza, sorry, I have to look after my well being. Guess what choice I will make? And that is where the cold facts come into place. I do try to avoid auditioning for conflicting roles, but it does occasionally come up. But as soon as I hear something I relay that info to the director of the non-paying gig. That is what really sucks about not having a budget for talent. But if both roles are paying, regardless of amount, the first one cast is priority. Heck even if it was just $20 bucks or gas money.
And in the future, I would always make sure to factor that aspect in. Hey, actors have to live too.
I guess the best analogy is: You have two competing gigs as a "fill in the blank". One is paying, the other is not. You have bills to pay. Which one do you choose? Unfortunately business and art do collide sometimes. Sure we can have an altruistic view of it, and claim it is strictly the art that rules.
But many artists also look at what they do as a source of income as well. No, they didn't sell out. They are scrambling to make ends meet, like all the rest of us. You can't begrudge an actor for choosing not to have to eat Top Ramen for a week, over maybe something better.
Look, you got 4 days notice. It is better than just not showing up. But before you judge them too harshly, maybe you ask if you truly know the situation they were in.