That is all up to you, and personally I think Thai tax office also does not care very much.
But in case you try to live in Thailand on a DTV it might be good to know that Thai tax office just has the possibility to tax you if they start caring about it.
For digital nomads it normally is not a problem, because they often leave before becoming tax resident.
DTA's just can be complex, type of income can make difference, some types of income can be taxed in Germany, some in Thailand, some in both.
Only when you exactly know the details of the DTA you will know what has to be done in Germany and what in Thailand.
I don't know the contents of the German DTA, but I do know about the Dutch DTA and I can assure you DTA's can be much more complex than you see at first sight.
That he is Norwegian is a fact, but about job and income we just miss all facts, we only know he gets "income" from a "foreign" company and it is less than average. Not if it is a salary, not a type of job contract, not a nationality of the company, no indication about how much less than average.
Too much uncertainties and assumptions for me to tell this is a good case or a bad case.
There wi;ll certainly be experts, but a facebook group is not the first place to look for such experts.
People in FB groups don't share enough info online which is understandable, and the for the real experts it is their job and they won't give free advise here, which is also understandable.
And personally I think that when you use DTV to its limits, you should just consult an expert, not doing so might result in unpleasant surprises, and that has nothing to do with playing with fear of people.