Entirely to many variables and personalities to consider without knowing more about Company Z.

I find that honesty is key in these type of scenarios.
Just recently I was offered a job flying after I had signed a 2 yr commitment to instruct. On the face of it, I'm silly not to take the job flying, but when I explain why I must turn down the offer "at this time" it clarifies where you are coming from.
- keeping your word and commitment
- people put their name on the line for you.
- family commitments

So long story short.....if Company Z took it negatively and refused to talk with you, then it shows something about who they are and likely you don't want to work for them