From this description it sounds like you did not interfere, but that stepdaughter had her doubts and asked for a second opinion. It`s odd that her own father apparently wants to screw over (financially) his child. And the anger he has is not so much about the alleged intrusion, but rather for missing out on a financial bonus? (guessing here)
Now, as to the wife, that`s different - but you could - when both are calm - present the case that it`s better to be self employed, than bound by a contract with several very negative options for her daughter.
I see this not so much as 'encouraging her career' but rather 'help her realize her gut feeling was right, and pointing out WHY it was right'.
So, the only issue you have is make peace with your wife - and keep supporting the stepdaughter here - as it seems her father does not have her best interests at heart.
NTA