No, your attempt has drastically failed you. Your claim that hyphenating it is wrong is false. That is why there are so many discussions on it, most of which conclude that either hyphenating it or italicizing it is proper. They even use quotes from publications supporting the stance:
"It’s not incorrect to hyphenate Latin phrases, but it’s unnecessary."
http://www.languageediting.com/hyphenation-of-latin-phrases/
https://forum.wordreference.com/threads/in-vitro-in-vivo-hyphens-in-modifiers.1541663/
Remember, you're the one who claimed that hyphenating it is wrong. Yet there are sources claiming that it isn't wrong to do so and others claiming that it is the correct way.
No longer requiring it doesn't make it wrong to continue to do. This is why you're a tier three graduate. You simply don't have the intellect to understand things intelligent people do.
If you're no longer required to wear a tie to work, as the rule was before, is it wrong to wear a tie to your work? Of course not. If you're no longer required, by some guides, to italicize/hyphenate a phrase, is it wrong to continue doing so? Exactly.
You're the one who claimed it was wrong. That's simply false.
Oh, and those sources you listed . . . there are examples of some of those using "in-vitro," so that blows away that argument as well.
The next time you try correcting somebody far more intelligent than you, you better make sure what you're attempting to correct something that is truly wrong or else you look dumber than even a tier three law grad.