No it is not. It's like saying a Ferrari in third gear will be faster than a Fiat in third gear, because Ferrari. Clearly this is not the same as saying that "therefore a Ferrari is as good as a Fiat", because obviously Fiat only goes up to gear three whereas Ferrari goes up to 7. But chant the "Ferraris are always faster" mantra without this context, and eventually all but your most technical users will be the kind of user who sticks to the third gear that they're used to, and still expect a Ferrari to be fast.

You want your Ferrari to go fast? Drive it like a Ferrari.

Also, Python absolutely can be as performant as Julia, if not more. The point is that Julia has language-builtin features that were created with this performance in mind, whereas for Python you have to go explore the relevant package ecosystem and go down a numba/cython/pypy/etc route.

And, yes, if you bragged how a Fiat could never beat your Ferrari in a race, and you agreed to race me against my modified Fiat with external turbo engines and I beat the crap out of your Ferrari, your "well that wasn't really a Fiat" complain would be valid, but only so much. Especially if Fiats were super-moddable by nature.