No that's bullshit and it shows you never have done it.
Tensorflow is CUDA only and does not run over AMD GPU. Because CUDA is proprietary and has a monopoly on GPGPU for now.
It is such a big deal that AMD had to fork tensorflow and try to make their own version it in order to make it "partially" run over HIP. This naturally makes it behind upstream, buggy and partially updated [^1]
CUDA is not portable and will never be.
The sad truth is that, due to CUDA, a big majority of GPGPU programs are now vendor lock-in on Nvidia hardware. That is unacceptable, but it is like that.
[^1]: https://github.com/ROCmSoftwarePlatform/tensorflow-upstream