Good news!

Me and my wife visited the surgeon this morning to get clarification and confirmation on actual existence of cancer. We told the surgeon that the cancer center in Japan cannot provide any second opinion or treatment advice without confirmed Melanoma biopsy.

The surgeon said that the nose is healing very well and is clear of any discoloration, and therefore without any signs of melanoma. He took samples from the nose near where he removed the polyp for biopsy to remove any doubts.
An MRI scan will be done next week Thursday after which we have an appointment to review the biopsy report and the scan findings.

The chemo oncologist suggestions of treatment are all based on the initial statement of the surgeon that melanoma was found in the polyp, and the result of the PET scan.
The surgeon confirmed that the PET scan taken 1.5 weeks after operation was meant to see if the cancer had spread anywhere, not to confirm cancer in the nose.

In the experience of my wife, who lost her mother and grandparents to cancer, all this is very different procedure as would have been done in Japan. Specialists here immediately jump to the worst conclusion and engage their own team of oncologists to provide advice. In Japan the doctors follow a different protocol, carefully weighing information and preventing over-treatment due to a point based merit-demerit system implemented by the Japanese government.

HR should be made aware of this typical specialist behavior in Singapore, and together we can learn from this episode to not jump to conclusions simply because of one private specialist's opinion.

I do want to repeat that I have informed HR with facts and that the suspicious results of the tests and opinion of the surgeon were reported without asking for confirmation.
It was not known to me that when a doctor in Japan provides such diagnosis, it is usually a signal that it's very very serious, and hence I do understand the reaction of HR.
Apparently in Singapore one need to ask a lot of questions and resist following (expensive) private specialist advice and referrals to oncologists. This difference in culture is all new to me and my wife.

I would never have reported suspicious opinions of specialists if the reaction from HQ would be so drastic. Honesty and inexperience in this respect should not be punished with a premature repatriation decision.