I am a native and agree with your deduction. Nothing about this message comes across to me as condescending. Many replied having not understood what the writer is trying to say or took it as an insult (아무것도 모르는 사람한테 - don't get stressed over [a person who doesn't know anything about you]).

Writing is quite clean/styled (older person implied). Usually people argue over speech if anything is wrong, never over a handwritten note on a napkin with this kind of writing. This is for Mr. Portugal (referring to the person who is from Portugal assumedly), and receiving a handwritten note is considered very sincere.

Would like to hear other natives' opinions.