@Nermie01:
From what I read in the first chapter the MC wanted to get a "normal" profession - something like "Merchant", "Farmer", "Hunter", "Cook" etc.
So a job that would allow him to live his life without having to worry too much about earning enough to live but at the same time not making him stand out or forcing him to risk his life for the job.
So any profession like "mage", "warrior" or "knight" etc. were out from the beginning due to the risk they would involve and due to the public recognition (for example for a successful mage or knight).
But the MC would have liked to avoid the title of "Slave Merchant", too, because it is a pretty "famous" profession that will in turn gather attention that he would like to avoid.
Also usually you would only choose "Slave Merchant" if you had no other viable choice or if you have a reason to not take the other choices.
In the later case people would expect you to reveal the other choices (like the elf girl did in this chapter revealing that she had respectable alternative options).
So people would know that you have a good personality as can be seen from your other choices but you must have had a reason to not take those other choices.
That way people will still treat you respectful while viewing you as a "good person".
But the first case is the problem. If you have no alternative respectful choices for your profession so that "Slave Merchant" would be the most "respectable" choice among them then that would mean that your personality would only be fit for that suspicious profession or even worse professions.
Therefore people would become prejudiced against that kind of person.
And now comes the issue the MC has.
He wants to have a quiet life.
So he cannot reveal his alternative choices "Hero", "Demon Lord" or "Great Sage".
If he did he could forget about a peaceful and quiet life completely.
But without revealing his alternative choices for his profession the people will naturally put him into the catergory of persons that have only worse choices than "Slave Merchant" or no alternative choices at all.
And with that the people will judge him to be a "suspicious" and probably "malicious" person and treat him based on that kind of prejudice wthout even trying to get to know him first.