To be fair, you were not rigorous enough to call that a proof and I think you know that. So there's really no point in arguing semantics here, it's just giving maths a bad look.
> To be fair, you were not rigorous enough to call that a proof and I think you know that.
On the contrary. Referring to a well-known result without proving it in situ is very common. For example, I also assume without proving that if two integers a, b have the property that ka = kb, then a is equal to b. You don't see anyone complaining about that.
