Are the experiments described of transferring cancer cell nuclei into normal cells that stop dividing abnormally, and transferring normal cell nuclei into cancer cell cytoplasm and seeing them become cancerous and proliferate abnormally, revealing the truth about metabolic origin of cancer?

This indeed is the case. While it may appear to be a simplistic approach that could have many unseen pitfalls because it is still fairly crude, although elegant in the execution of maneuvers, it nonetheless is a useful read-out that is lining up perfectly with the idea that the dysregulation of cancerous cells resulting in a profitless proliferation that goes unchecked is not coming from gene expression per se. There are gene changes in support of what happens, but the true causal elements are metabolic, taking place within the cytoplasm, and then impinging on the nucleus to stimulate changes in gene expression, so the latter are a consequence and not a cause of the abnormal cellular behavior.