I don't see any rudeness, sarcasm I do see. I try to cut down on sarcasm, but I will never believe in "If you have nothing nice to say, don't say nothing at all." That saying died when Facebook started.
Thailand has only been taking very small steps. I think there will be no tourism as long as there is quarantine. And there probably will be quarantine for a long time, as all new cases were imported.
People who really need to be in Thailand on urgent matters have a better chance of more groups being allowed in than getting in on a tourist visa.
If you believe things will change much the next two months, I think you are wrong. Thailand does not seem to relax much as long as there is a problem in other countries. I think not much will change before 2021.
Better start putting your money in the bank. What if they do not give more amnesty? You are one of the lucky people who have an easy option, many people have no options this easy and cheap.
I saw many messages in Chiang Rai groups concerning this issue. It was not only Green bus, but some other companies had no problems with non-Thais. I did not hear this requirement has changed in the last few weeks, but it may very well have.
A few people asked why, but were not given a reason. My guess is their regular Thai customers are scared of foreigners.
In Chiang Rai they have the Green bus, not sure if they are everywhere in Thailand. Chiang Rai - Chiang Mai is an important busroute, but only Thai citizens can travel on the Green bus.
It does not seem to be a requirement from government, just a Xenophobic bus company.