What's your opinion on countries banning flights from India, which prevents their own nationals from returning home?
.New Zealand has decided not to extend its current ban under the belief that it is illegal to deprive the right of one's own citizens from returning home.
First of all, this is nothing new. In early 2020, most countries airlines including flag barriers stopped their flights from China, that essentially blocked their own citizens from returning. Neither did these countries organize any repatriation flights. One example is that some British vacationers got stranded in Thailand, run out of money, then left hotel and lived in a cave for some days.
Now before I give my opinion on your post I must lay down something about what China did, how China could do so.
I remember in the first half of 2020 when Chinese nationals began to return to China en mass due to the deteriorating situation in the west. Chinese government advised Chinese nationals to avoid travel, but never banned them returning. China always maintained one flight per week in and out of China to one destination/country. There were some Chinese citizens in China blaming the returnees for bringing back the virus and being selfish.
My opinion, there is no legal ground to ban a citizen returning own country from danger. It is absolutely illegal to do so. That is why Chinese government never did it. It is also selfish on the part of the people who advocate the banning. This is like keep one's brother/sister in the harms way to keep oneself safe.
On the other hand, the returnees have the obligation to follow the strict protocol set up by the government and provided by the embassies: test/mask/quarantine during and after their journey.
I believe in "few sacrifice for great good of many", but I also believe that without the many caring the few, the many does not deserve the sacrifice of the few. Every coin has its two sides. A state is not only a calculator for cost/gain, a state is the refuge of its people, the hope of an idea. Only by fulfilling that purpose does a state has reason to be.
On the technical ground. To let in the returnee, there must be a closed loop, that is from the moment of touch down, the returnee lives in an air-tight bubble until he/she is proven to be clean. China has the facility, most countries don't. That is a very hard choice for those countries. Examples of what enabled China to do so are: 1. Ramp up production of air-tight negative pressurized ambulance for transporting all suspected people. 2. Dedicated arrival terminals in the airport. 3. Divert incoming flights to different airport to spread out the quarantine load. All these are possible because China is a centralized state that the central government has absolute power. That is nowhere in the rest of world.
After talking this much, I can say that most countries have no way to match what China has done. So there is nothing good or bad, right or wrong if they block their own citizen returning, not a choice that anyone want to make.